a/c compressor not engaging

Deb
I have sent this out several times over the years.

"1973 through 1976 models had two relays in that area. The one above the horn is the blower relay for the heater/ air-conditioning blower.
Late 1977 and 1978 models had a third relay at the top which was a delay relay.

The delay relay is the smaller relay at the very top of the panel. It has two leads - on mine they are brown and yellow and one has a male and the other a female terminal at the end of the leads. The leads are approx. 6 to 8 inches long. The female one connects to the male terminal on the lead to the blower motor. The male one leads to the short lead (purple on mine) that goes to the blower relay (terminal 1). If the delay relay burns out you can plug the male motor lead directly into the short female lead going to terminal 1 on the blower relay.

The blower relay (below the delay relay but above the horn relay) has 5 terminals. When the blower relay is mounted with the 5 terminals down, there are two on the left, one in the middle and two on the right.

On the back left side it is #3 which has a red/white wire that leads to a fusible link and that goes into the harness and connects to the red wire from the alternator to the center stud of the battery isolator.

On the front left is terminal #2. Mine has a dark blue wire that leads to the resistor package in the right side of the heater box.

In the center is terminal #1. Mine has a short purple wire with a female connector. The male lead from the delay relay plugs into this (on mine right now I have the blower motor plugged into this as my delay relay is bad and disconnected).

On the right rear is terminal #5. This has a short black lead that goes to a ground screw.

On the right front is terminal #4. This has an orange wire that leads to the heater controls on the dash.

Terminals 4 & 5 control the coil in the blower relay.

Terminals 1 & 2 are normally closed and operate the blower when in low or medium speeds.

Terminal 1 & 3 are normally open but when the dash switch is put in "high" or "max" it actuates the coil and the relay connects these terminals which give power to the blower directly from the alternator in order to get higher voltage and higher blower speed. At the same time it disconnects terminal 2 from the circuit.

This may be more than you want to know but if you have any questions get back to me.”

Emery Stora
77 Kingsley
Frederick, CO

>
> Hi Ken. Well I have gone through the fan speed switch yesterday and appears to be fine. Today I worked my way back from the motor, since that, for
> me was the most direct and easiest to visualize.
> No power going to the motor from the delay relay.
> Checked the delay relay - power going in (the purple wire from the blower relay - now yellow from PO) and through that little "jumper" you see in the
> wiring diagram?
> Nothing coming from what was the purple hot wire - now black by PO - that goes through the capacitor to the motor. I pulled the harness and confirmed
> with the voltmeter that the harness looks good (12+ v across from the incoming 'jumper' to the outgoing 'ppl').
>
> Having some difficulty with the main blower relay - some re-wiring underneath is making it a bit difficult to access half sideways/upside down and my
> eyes are getting very tired from the close up focus (have to dig out my really close-up cheaters!). But since the current goes through that to the
> delay relay, I know that it is at least partly working.
>
> Once my eyes are uncrossed, I need to check the wire between the fan switch to the relay (green by the diagram) and the blue going to (coming from?)
> the resistor pack
>
> I did pull the resistor just because it was easier than checking with the MM and test light. The coils are intact. The harness is FILTHY!
>
> Before I tried it, I wanted to see if it is a reasonable move to by-pass the delay relay with a jumper wire in the harness to see if that gets me
> power down the line to the motor. I see in the parts interchange that the delay relay shows as 'obsolete' and doesn't seem to have an alternative?
> What to do if it is toast? Can it be by-passed?
> --
> Deb McWade
> Logan Lake, BC, CAN
> "Li'l Sister"
> '77 Kingsley, 403, EBL EFI;
> TZE167V101404
> It's Bigger on the Inside!
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Figured if that relay can be by-passed completely, it wouldn't hurt to try it and see.... Paper-clip in place, restarted the coach and we had
blower!
http://www.gmcmhphotos.com/photos/data/7218/IMG_27451.jpg
http://www.gmcmhphotos.com/photos/data/7218/IMG_2729.jpg
Now I guess figure the best way to by-pass it. Cut it out altogether and use a new spade connector, or by pass it in the harness (on the off chance
there is a good used relay out there somewhere someday)?

--
Deb McWade
Logan Lake, BC, CAN
"Li'l Sister"
'77 Kingsley, 403, EBL EFI;
TZE167V101404
It's Bigger on the Inside!
 
Deb,

Emery recently provided instructions here for someone to bypass that relay
very simply. I've never had one, so I can't tell you those details. But
you just need to identify the input and output leads and connect them (as
you apparently did with a paper clip) permanently -- either with a reliable
connector or by splicing the wires. And protect the disconnected control
leads with tape so they can't short.

Congratulations on your success! ;-)

Ken H.

On Sun, Jul 14, 2019 at 4:13 PM Deb McWade via Gmclist <

> Figured if that relay can be by-passed completely, it wouldn't hurt to try
> it and see.... Paper-clip in place, restarted the coach and we had
> blower!
> http://www.gmcmhphotos.com/photos/data/7218/IMG_27451.jpg
> http://www.gmcmhphotos.com/photos/data/7218/IMG_2729.jpg
> Now I guess figure the best way to by-pass it. Cut it out altogether and
> use a new spade connector, or by pass it in the harness (on the off chance
> there is a good used relay out there somewhere someday)?
>
>
>
>
>
> --
> Deb McWade
> Logan Lake, BC, CAN
> "Li'l Sister"
> '77 Kingsley, 403, EBL EFI;
> TZE167V101404
> It's Bigger on the Inside!
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Very well done indeed!! Ill have to check to see if mine has this relay and bypass it as well....one less thing to worry about failing in the long
run (if it hasnt already....lol).
--
Rich Mondor,

Brockville, ON

77 Hughes 2600
 
Thanks Ken. Small job in comparison to most of what I read, but feels good to work my way through something, with lots of direction I might add. And
I have learned a lot about the electrical in this coach. Not a speck of what many of you have to offer, but still. Feels good. Every time I manage
to accomplish something with the old girl, I am less hesitant to take on something else. While I have half the dash apart, I might take a look at the
instrument cluster lights. Fuse is good - After market radio? (read something about confusing the grey wire for the instrument lights with a ground
wire) or maybe the headlight switch has a bad rheostat.

Tomorrow I will pull the blower and take a look in there. I wouldn't doubt it could use a good cleaning out. The 'hamster wheel' often gets clogged,
from what I have heard?

I suppose that it could just be coincidence that the relay crapped out while I was working on the ac a/c recharging (which is still a work in
progress, and what started this entire thread). Or maybe the blower is old, tired and dirty. Brushes? Or who knows what? But I would like to see
if i can find a reason. Second time the motor has quit due to a burned-out something this summer. Looking forward to seeing what's 'behind the
curtain' so to speak.

I think there's no doubt the relay is hooped... (stinks too - that's the source of the melted plastic/over-heated wiring smell!)
http://www.gmcmhphotos.com/photos/data/7218/IMG_27471.jpg

Since it's gone to a better place, I might just take it apart.
--
Deb McWade
Logan Lake, BC, CAN
"Li'l Sister"
'77 Kingsley, 403, EBL EFI;
TZE167V101404
It's Bigger on the Inside!
 
Bypass the relay and be done with it. 76 and earlier coaches did not even have one. I had a similar issue with a pair of switches on one of our zero
turn lawn mowers. The switches shut off the deck when going in reverse. They used the same type of connector that you have there. I got two spade
connectors and crimped them on a 2" long 14 ga. wire. Then I plugged that jumper into the socket. I later found out that they eliminated those
switches on the newer version of that mower.

Do the same thing here. Use 14 gauge wire and make up a plug in jumper and replace the paper clip.

Now back to the Duracool charging questions.......
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
> Bypass the relay and be done with it.
>
> Now back to the Duracool charging questions.......

Done ;) Using the original ground connection to hold it up and will add a second support to the other relay screw to keep it from swinging in the
breeze.

Pulled the motor and aside from some dirt inside the motor (banged the 'hamster wheel' carefully several times on a towel and got a fair amount of
fine dust out of the motor itself as well as took an old toothbrush to the fins.) The wheel turns pretty easily. How freely should it spin? If I
gave it a good turn, should it stop within about a single revolution or should it go for a couple of turns or more?

Any other cleaning? Take the air compressor to it and blow any loose crud out? I'll pop the front motor casing off the heater/evaporator housing and
clear that out while I'm at it.

And restart the Duracool saga tomorrow. I suspect a leak, so it may be a short morning.

Thanks to all for the help with the blower.
--
Deb McWade
Logan Lake, BC, CAN
"Li'l Sister"
'77 Kingsley, 403, EBL EFI;
TZE167V101404
It's Bigger on the Inside!
 
> Deb
> I have sent this out several times over the years.
>
> "1973 through 1976 models had two relays in that area. The one above the horn is the blower relay for the heater/ air-conditioning blower.
> Late 1977 and 1978 models had a third relay at the top which was a delay relay.
>
> The delay relay is the smaller relay at the very top of the panel. It has two leads - on mine they are brown and yellow and one has a male and the
> other a female terminal at the end of the leads. The leads are approx. 6 to 8 inches long. The female one connects to the male terminal on the lead
> to the blower motor. The male one leads to the short lead (purple on mine) that goes to the blower relay (terminal 1). If the delay relay burns out
> you can plug the male motor lead directly into the short female lead going to terminal 1 on the blower relay.
>
> The blower relay (below the delay relay but above the horn relay) has 5 terminals. When the blower relay is mounted with the 5 terminals down,
> there are two on the left, one in the middle and two on the right.
>
> On the back left side it is #3 which has a red/white wire that leads to a fusible link and that goes into the harness and connects to the red wire
> from the alternator to the center stud of the battery isolator.
>
> On the front left is terminal #2. Mine has a dark blue wire that leads to the resistor package in the right side of the heater box.
>
> In the center is terminal #1. Mine has a short purple wire with a female connector. The male lead from the delay relay plugs into this (on mine
> right now I have the blower motor plugged into this as my delay relay is bad and disconnected).
>
> On the right rear is terminal #5. This has a short black lead that goes to a ground screw.
>
> On the right front is terminal #4. This has an orange wire that leads to the heater controls on the dash.
>
> Terminals 4 & 5 control the coil in the blower relay.
>
> Terminals 1 & 2 are normally closed and operate the blower when in low or medium speeds.
>
> Terminal 1 & 3 are normally open but when the dash switch is put in "high" or "max" it actuates the coil and the relay connects these terminals
> which give power to the blower directly from the alternator in order to get higher voltage and higher blower speed. At the same time it disconnects
> terminal 2 from the circuit.
>
> This may be more than you want to know but if you have any questions get back to me."
>
> Emery Stora
> 77 Kingsley
> Frederick, CO

The first time I saw this post, it didn't make a lot of sense to me. Who am I kidding - my eyes glazed over and I pretty much quit after "If the
delay relay burns out you can plug the male motor lead directly into the short female lead going to terminal 1 on the blower relay.". But after 3
days of pouring over the manual, wiring diagrams, tracing coloured wire, and playing with the test light and MM under there, there is a light bulb
coming on! ? So far, the main blower relay seems OK, but so was the delay relay last week.

I really appreciate having your "road map" of the underside of the relay, since it's impossible to see under it without removing it (I keep reminding
myself to get a mirror and practice working in reverse - helpful for dash wiring too I reckon). My PO has changed out a few wires here and there
(nothing creative, like some! Just replaced old wiring) and it's hard for a raw recruit to follow the wiring diagrams when the wire colours are not
the original & they can't show the terminal placement on the bottom of the relay.

Keep 'em comin' Emery!
--
Deb McWade
Logan Lake, BC, CAN
"Li'l Sister"
'77 Kingsley, 403, EBL EFI;
TZE167V101404
It's Bigger on the Inside!
 
Hopefully, this thread can now come to an end. There is no leak in the low pressure tube that I can find at the point I suspected - no bubbles & it
has held it's static pressure at roughly 60 psi , which was where it was before the past few days of trouble-shooting the blower. I did clean the
connections on the low pressure cut-off switch to make sure I got a good connection.

Started her up and running low side started at 25 psi and slowly climbed to 30, where it sat for 15 minutes. I started just running the a/c on Norm
with the fan speed at high. Since everything seemed to be going well, I popped it into Max. Ran like that for another 10 minutes. Low side running
holding nicely at 30 psi.

Looks like my initial problems were:
1 Not enough refrigerant so the compressor wouldn't kick in. By-passed the switch and she worked fine. Added a can of R12a to get the volume up to
minimum.
2 Plugged the low pressure switch back in after adding a can. Then the clicking of the switch started.
3 Then the blower quit (may have been completely coincidental).

So now, cleaned the connections on the low pressure switch in case after disconnecting it, I lost a good connection. No more clicking. Blower
working well (knock wood). An air leak around the motor casing and at the cooling hose (not big, but I would like to seal those up) and the a/c
blowing nice, cold air again.

Since I did lose some refrigerant over the winter, I obviously have a leak (small) somewhere. But at this point, I am going to leave well enough
alone!

Thanks to all.

Next job - replace the LOP switch and oil filter adapter gaskets and starter bracket on the Onan. But those may also wait till after my trip to
Washington.
--
Deb McWade
Logan Lake, BC, CAN
"Li'l Sister"
'77 Kingsley, 403, EBL EFI;
TZE167V101404
It's Bigger on the Inside!
 
If you are at 30 psi at 1500 rpm you can likely get it cooler if you drop the pressure to perhaps 25 psi.
Your leak over the winter is likely from the seal on the clutch. The oil keeps this from leaking but if it sets over a winter it can dry out and leak a little. If you start the air conditioner once a month the seal will get lubricated and may solve your slow leak problem.

Emery Stora

>
> Hopefully, this thread can now come to an end. There is no leak in the low pressure tube that I can find at the point I suspected - no bubbles & it
> has held it's static pressure at roughly 60 psi , which was where it was before the past few days of trouble-shooting the blower. I did clean the
> connections on the low pressure cut-off switch to make sure I got a good connection.
>
> Started her up and running low side started at 25 psi and slowly climbed to 30, where it sat for 15 minutes. I started just running the a/c on Norm
> with the fan speed at high. Since everything seemed to be going well, I popped it into Max. Ran like that for another 10 minutes. Low side running
> holding nicely at 30 psi.
>
> Looks like my initial problems were:
> 1 Not enough refrigerant so the compressor wouldn't kick in. By-passed the switch and she worked fine. Added a can of R12a to get the volume up to
> minimum.
> 2 Plugged the low pressure switch back in after adding a can. Then the clicking of the switch started.
> 3 Then the blower quit (may have been completely coincidental).
>
> So now, cleaned the connections on the low pressure switch in case after disconnecting it, I lost a good connection. No more clicking. Blower
> working well (knock wood). An air leak around the motor casing and at the cooling hose (not big, but I would like to seal those up) and the a/c
> blowing nice, cold air again.
>
> Since I did lose some refrigerant over the winter, I obviously have a leak (small) somewhere. But at this point, I am going to leave well enough
> alone!
>
> Thanks to all.
>
> Next job - replace the LOP switch and oil filter adapter gaskets and starter bracket on the Onan. But those may also wait till after my trip to
> Washington.
> --
> Deb McWade
> Logan Lake, BC, CAN
> "Li'l Sister"
> '77 Kingsley, 403, EBL EFI;
> TZE167V101404
> It's Bigger on the Inside!
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
> If you are at 30 psi at 1500 rpm you can likely get it cooler if you drop the pressure to perhaps 25 psi.
> Your leak over the winter is likely from the seal on the clutch. The oil keeps this from leaking but if it sets over a winter it can dry out and
> leak a little. If you start the air conditioner once a month the seal will get lubricated and may solve your slow leak problem.
>
> Emery Stora

Thanks Emery. I will try releasing a bit of refrigerant tomorrow. And I had never thought of running the ac in the winter. I'll try that this
winter and see how it looks next spring. With a leak this slow, if it's just a matter of topping it up a bit each season, I can live with that for
now. But if running the compressor occasionally will prevent that, happy to do it. My coach just sits from Oct/Nov to Apr/May, depending on when the
snow comes and melts. Can't do much with her in the winter up here. Sometimes I shovel a path to the door and go in and sigh! :cry:
--
Deb McWade
Logan Lake, BC, CAN
"Li'l Sister"
'77 Kingsley, 403, EBL EFI;
TZE167V101404
It's Bigger on the Inside!
 
I believe MOST current vehicles with A/C installed will run the compressor even in winter at times to reduce humidity in the vehicle in DEFROST mode. Therefore Emery's recommendation probably applies primarily to older vehicles and our buggies are definitely in that category!

D C "Mac" Macdonald​
Amateur Radio K2GKK​
Since 30 November '53​
USAF and FAA, Retired​
Member GMCMI & Classics​
Oklahoma City, OK​
"The Money Pit"​
TZE166V101966

________________________________
From: Gmclist on behalf of Deb McWade via Gmclist
Sent: Monday, July 15, 2019 13:39
To: gmclist
Cc: Deb McWade
Subject: Re: [GMCnet] a/c compressor not engaging

> If you are at 30 psi at 1500 rpm you can likely get it cooler if you drop the pressure to perhaps 25 psi.
> Your leak over the winter is likely from the seal on the clutch. The oil keeps this from leaking but if it sets over a winter it can dry out and
> leak a little. If you start the air conditioner once a month the seal will get lubricated and may solve your slow leak problem.
>
> Emery Stora

Thanks Emery. I will try releasing a bit of refrigerant tomorrow. And I had never thought of running the ac in the winter. I'll try that this
winter and see how it looks next spring. With a leak this slow, if it's just a matter of topping it up a bit each season, I can live with that for
now. But if running the compressor occasionally will prevent that, happy to do it. My coach just sits from Oct/Nov to Apr/May, depending on when the
snow comes and melts. Can't do much with her in the winter up here. Sometimes I shovel a path to the door and go in and sigh! :cry:
--
Deb McWade
Logan Lake, BC, CAN
"Li'l Sister"
'77 Kingsley, 403, EBL EFI;
TZE167V101404
It's Bigger on the Inside!

_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Thanks Mac. I thought I had read something along those lines in my a/c researching. Not a surprise ours is a different animal is it? :)
--
Deb McWade
Logan Lake, BC, CAN
"Li'l Sister"
'77 Kingsley, 403, EBL EFI;
TZE167V101404
It's Bigger on the Inside!
 
Just an update on the a/c story. Trip down to WA state and the a/c was excellent. Frosty knees even with the heater hose open (I have a lever ball
valve in the line to the heater core since my OEM vacuum valve packed it in last summer). And I found a delay relay NOS on eBay. Just put it in and
it works perfectly. Might try to track down one of those vacuum valves for the heater hose on eBay too. Never know. Would make it easier to toggle
between true maximum a/c and heat when on the road, in the mountains, in the summer :)

Thanks again for all of the assistance on this guys.
--
Deb McWade
Logan Lake, BC, CAN
"Li'l Sister"
'77 Kingsley, 403, EBL EFI;
TZE167V101404
It's Bigger on the Inside!
 
For what it's worth, your pictures show a common failure in that construction of relays. the dissimilar metals have dissimilar expansion rates and if
the relay is subjected to heating/cooling cycles the problem will speed up. The expansion/contraction loosens the rivet which holds the thing
together, a minor amount of corrosion appears, and you have a small but powerful electric heater. Note in the second picture, the actual contacts
don't look bad, what can be seen of them, but the riveted connection has gone Dixie in a rathjer smelly fashion.
Smell often points up a problem before it's visible.

--johnny

--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
 
Once you get the fan issue solved, run it on HI to keep evaporator from getting too cold and cycling the compressor. Only use the reading you get
while compressor clutch is engaged and then once it stabilizes. I assume you have 134a adaptor fittings? If so the Harbor Freight manifold set is not
that bad for quality (except for outer vinyl layer on hoses that split in 9 months). Those in line low side fill hose gauges can be pretty vague.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
Thanks John. She is running and cooling very well but still very good info on checking running pressures. I can get a decent gauge set at Princess
Auto up here and something I will pick up before next a/c season.
--
Deb McWade
Logan Lake, BC, CAN
"Li'l Sister"
'77 Kingsley, 403, EBL EFI;
TZE167V101404
It's Bigger on the Inside!
 
Re the delay relay. You can simply repatch the connectors around it and leave it there. It was a retrofit add on in 77. It was to allow the dash vent
door to open by vacuum before the Hi blower blast fought the door when going from OFF to MAX AC. The simple fix is to go to NORM AC first using a
lower fan speed then move it to MAX. I never use OFF position and leave mine in VENT as a default. I want fresh air coming in whenever coach is
running. This works driving on cool mornings where you can warm the air as needed, then go to cold outside air as sun warms and then just move lever
to NORM AC as the greenhouse heats up. You will get slightly less voltage drop by eliminating the delay as every connection and added wire drops it a
tenth or so. It adds up
--
John Lebetski
Woodstock, IL
77 Eleganza II