Help me troublshoot roof AC unit and furnace

A

adam

New member
Oct 23, 2011
13
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She has been sitting for probably 10 years or more. I'm going through it now to see what works and what doesnt. Most of the stuff does.

Rooftop AC turns on and blows, but the compressor never kicks on. I want to determine if its just lost freon or if theres another problem. Whats the easiest way to check? Any common problems? I have a buddy that works on home AC systems, how simmilar will this be?

Furnace wont light. According to the owners manual, I turned on the valve at the tank (shows 3/4 full and I can open up the overflow valve and hear and smell gas) open up the valve at the furnace, push reset button, and press igniter a bunch of times. The igniter is sparking, but nothing lights. Seems like gas is not getting to the burner. Where do I start troubleshooting? Any common problems?

Fridge seems to be working (turned on for an hour, freezer compartment was getting chilly) most lights work except for the lights by your feet along with whatever the 2 switches by the door are supposed to turn on (one turns on the outside door light, which works) Water pump turns on. I'll put some water in the tank and check to make sure it pumps and no leaks, and check water heater, sinks, and toilet.


Oh, and the flush on the toilet is stuck. Foot pedal is stuck, I dont want to push hard and break anything. I was hoping to maybe put some water in the toilet and maybe it would free up? Or what should try?


Thanks for your help!
 
> She has been sitting for probably 10 years or more. I'm going through it now to see what works and what doesnt. Most of the stuff does.
>
> Rooftop AC turns on and blows, but the compressor never kicks on. I want to determine if its just lost freon or if theres another problem. Whats the easiest way to check? Any common problems? I have a buddy that works on home AC systems, how simmilar will this be?
>
> Furnace wont light. According to the owners manual, I turned on the valve at the tank (shows 3/4 full and I can open up the overflow valve and hear and smell gas) open up the valve at the furnace, push reset button, and press igniter a bunch of times. The igniter is sparking, but nothing lights. Seems like gas is not getting to the burner. Where do I start troubleshooting? Any common problems? Should the blower fan turn on when I turn the temp up on the thermostat, even if the furnace is not lit? Because it does not.
>
> Fridge seems to be working (turned on for an hour, freezer compartment was getting chilly) most lights work except for the lights by your feet along with whatever the 2 switches by the door are supposed to turn on (one turns on the outside door light, which works) Water pump turns on. I'll put some water in the tank and check to make sure it pumps and no leaks, and check water heater, sinks, and toilet.
>
>
> Oh, and the flush on the toilet is stuck. Foot pedal is stuck, I dont want to push hard and break anything. I was hoping to maybe put some water in the toilet and maybe it would free up? Or what should try?
>
>
> Thanks for your help!

what model furnace is it? usually you turn up the stat and the blower starts and it ignites.

pour a bit of olive oil on the toilet seal and let it sit.

--
Fred V
'77 Royale RB 455
P'cola, Fl
 
Adam, if the Roof AC is a Duo Therm, it has a two minute delay timer that
delays the compressor starting for a full two minutes after the unit is
started. If your unit's compressor does not start after a 2 minute test,
the relay is probably full of dust and the contact points just need
cleaning. Take the plastic outer cover off the unit, and from the drivers
side of the coach, you will find a galvanized electrical box with a single
sheet metal screw holding the cover on. Remove the screw and the cover,
spray contact cleaner into the relay contacts, and follow up with a blast
of compressed air. Working on a dead circuit, open the contacts, and draw a
piece of clean white card stock like a business card through the contacts
to remove all residue. Restart the AC unit and observe the relay and time
it with the sweep hand on your watch. If the relay pulls in and the
compressor does not start, service the compressor.
Jim Hupy
Salem, OR
78 GMC Royale 403

>
>
> She has been sitting for probably 10 years or more. I'm going through it
> now to see what works and what doesnt. Most of the stuff does.
>
> Rooftop AC turns on and blows, but the compressor never kicks on. I want
> to determine if its just lost freon or if theres another problem. Whats
> the easiest way to check? Any common problems? I have a buddy that works
> on home AC systems, how simmilar will this be?
>
> Furnace wont light. According to the owners manual, I turned on the valve
> at the tank (shows 3/4 full and I can open up the overflow valve and hear
> and smell gas) open up the valve at the furnace, push reset button, and
> press igniter a bunch of times. The igniter is sparking, but nothing
> lights. Seems like gas is not getting to the burner. Where do I start
> troubleshooting? Any common problems?
>
> Fridge seems to be working (turned on for an hour, freezer compartment was
> getting chilly) most lights work except for the lights by your feet along
> with whatever the 2 switches by the door are supposed to turn on (one turns
> on the outside door light, which works) Water pump turns on. I'll put
> some water in the tank and check to make sure it pumps and no leaks, and
> check water heater, sinks, and toilet.
>
>
> Oh, and the flush on the toilet is stuck. Foot pedal is stuck, I dont
> want to push hard and break anything. I was hoping to maybe put some water
> in the toilet and maybe it would free up? Or what should try?
>
>
> Thanks for your help!
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
 
this might help
http://www.gmcmhphotos.com/photos/showphoto.php?photo=7003&cat=3615

http://goo.gl/Dz65N

gene

> Rooftop AC turns on and blows, but the compressor never kicks on. I want
> to determine if its just lost freon or if theres another problem. Whats
> the easiest way to check? Any common problems? I have a buddy that works
> on home AC systems, how simmilar will this be?
>
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://bdub.net/gmcmotorhome.info/
Alternator Protection Cable
http://bdub.net/gmcmotorhome.info/APC.html
 
Not sure what model furnace is in it, looks original.

Those series of pictures, is that showing how to bypass the time delay relay? So the compressor comes on with no delay?
--
73 Sequoia 260
 
> She has been sitting for probably 10 years or more. I'm going through it now to see what works and what doesnt. Most of the stuff does.
>
> Rooftop AC turns on and blows, but the compressor never kicks on. I want to determine if its just lost freon or if theres another problem. Whats the easiest way to check? Any common problems? I have a buddy that works on home AC systems, how simmilar will this be?
>
> Furnace wont light. According to the owners manual, I turned on the valve at the tank (shows 3/4 full and I can open up the overflow valve and hear and smell gas) open up the valve at the furnace, push reset button, and press igniter a bunch of times. The igniter is sparking, but nothing lights. Seems like gas is not getting to the burner. Where do I start troubleshooting? Any common problems? Should the blower fan turn on when I turn the temp up on the thermostat, even if the furnace is not lit? Because it does not.
>
> Fridge seems to be working (turned on for an hour, freezer compartment was getting chilly) most lights work except for the lights by your feet along with whatever the 2 switches by the door are supposed to turn on (one turns on the outside door light, which works) Water pump turns on. I'll put some water in the tank and check to make sure it pumps and no leaks, and check water heater, sinks, and toilet.
>
> Oh, and the flush on the toilet is stuck. Foot pedal is stuck, I dont want to push hard and break anything. I was hoping to maybe put some water in the toilet and maybe it would free up? Or what should try?
>
> Thanks for your help!

Adam,

The First Thing you need to do is identify the maker and model of ALL the installed equipment. Then go to the Bdub site and find the manuals for everything. Many contain troubleshooting guides.

Also download the coach manuals, you can't beat the price.

The Roof unit is not indicating that it has lost charge by not starting - they don't have that feature. If it does not pop the breaker, then the compressor is not locked up. Go after the controls.

If the water pedal moves freely, but the blade valve does not, yes olive oil is a good start, but it may be helped by tapping the visible blade. If that doesn't do it, it may need a rebuild. (After you get the manual - it can be downloaded at thetford.com.) The unfortunate fact is that the seals sometimes get sticky with age and stick to the plastic valve blade. The parts kit is not that expensive.

Before you do much with the LP system, get some clear hose, a yard stick and some elastic bands to make a manometer and check the service pressure. This is real simple and if it wrong (common to a regulator left idle to a long time), it will cause no end of grief.

Matt
--
Matt & Mary Colie
'73 Glacier 23 Chaumiere (say show-me-air) Just about as stock as you will find
SE Michigan - Twixt A2 and Detroit
 
Do as Matt suggests download the circuits for the A/C and heater if your buddy is an A/c mechanic he will have no problem figuring out the problems with both.

--
Roy Keen
Minden,NV
76 X Glenbrook
 
When I brought my coach home, neither of the two AC's worked. On advice of another GMC'r, here is what I did.

http://www.gmcmhphotos.com/photos/showgallery.php?cat=3615

They both worked fine after this mod for the next 5 yrs. Then one compressor burned up and I replaced both with a single 15K.

HTH


> She has been sitting for probably 10 years or more. I'm going through it now to see what works and what doesnt. Most of the stuff does.
>
> Rooftop AC turns on and blows, but the compressor never kicks on. I want to determine if its just lost freon or if theres another problem. Whats the easiest way to check? Any common problems? I have a buddy that works on home AC systems, how simmilar will this be?
>
> Furnace wont light. According to the owners manual, I turned on the valve at the tank (shows 3/4 full and I can open up the overflow valve and hear and smell gas) open up the valve at the furnace, push reset button, and press igniter a bunch of times. The igniter is sparking, but nothing lights. Seems like gas is not getting to the burner. Where do I start troubleshooting? Any common problems? Should the blower fan turn on when I turn the temp up on the thermostat, even if the furnace is not lit? Because it does not.
>
> Fridge seems to be working (turned on for an hour, freezer compartment was getting chilly) most lights work except for the lights by your feet along with whatever the 2 switches by the door are supposed to turn on (one turns on the outside door light, which works) Water pump turns on. I'll put some water in the tank and check to make sure it pumps and no leaks, and check water heater, sinks, and toilet.
>
>
> Oh, and the flush on the toilet is stuck. Foot pedal is stuck, I dont want to push hard and break anything. I was hoping to maybe put some water in the toilet and maybe it would free up? Or what should try?
>
>
> Thanks for your help!


--
Larry :)
78 Royale w/500 Caddy
Menomonie, WI.
 
I opened up the AC electronics to find someone already had taken out the TDR, and looks like they also replaced the start relay and both capacitors. So why doesnt it work? The compressor never kicks on.

Maybe its wired wrong? Anybody have a simple wiring diagram of the modified setup with the TDR removed?
--
73 Sequoia 260
 
I forgot to add this photo of the electronics

http://www.gmcmhphotos.com/photos/uploads/11001/z1.jpg


Compared to the linked photo, only thing I can see righ off the bat is the blue and yellow wires are switched on the smaller capacitor. There are a few connectors on the capacitor that are unused I want to make sure its hooked up properly.
--
73 Sequoia 260
 
THE VOM is your friend. Basic circuit testing for voltages. You can also test the compressor out of circuit for opens on the OHMS side.
--
John Lebetski
Chicago, IL
77 Eleganza II
 
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