duffel
Northern Virginia
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Joined: 03/18/2005
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Hi! The front A/C unit in my motorhome isn't cooling. I've pulled the outside cover and cleaned the condenser coils (they weren't particularly dirty), fin combed out any irregularities in the fins, cleaned the evaporator filter (it wasn't particularly dirty either), and looked for any air leaks (none found). The unit starts okay, the fan runs fine with no noise or vibration. The compressor starts and runs (I put my hand on it an could feel it running and it does get warm). There does not seem to be any temperature differential between the copper supply and return lines to the compressor. This tells me that something is not right. However, I don't see any evidence of a refigerant (R22?) leak. The system is apparently sealed - at least I haven't been able to find any Schrader valves on the unit. So I'm out of ideas. Can anyone offer any suggestions on something I may have missed or someting new to try? Thanks, Tom Godbout
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kneal44
EAST CENTRAL TEXAS
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Joined: 01/24/2008
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can u measure current draw, to see if compressor is running. with the cover removed you should be able to feel the compressors vibration if running. also on my unit there must be a delay unit because when starting there is several minutes delay its called delay on make. this card may be faulty . tipical on home units .
first things to do is determine if compressor is running then check starting circuitry... be careful these voltages bite. hard.
john
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duffel
Northern Virginia
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John: Thanks for the reply. My A/C system works the same as yours. It takes a few minutes for the units to respond to instructions from the electronic thermostat. The compressor is running. I don't have an ammeter so I have no way of measuring current draw. In an effort to check the operation of the thermostat, I ran the demand temperature up to 90 degrees F. This caused the compressor to drop off the line. When I lowered the demand temperature back to 75 degrees F. the compressor came back on the line. Tom
Tom & Marta
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RPFAN
Poughkeepsie NY
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Joined: 04/02/2003
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Just because the compressor is running, does not mean it is working as it should. Compressor could be running but, not pushing freon thru the system. Also, this is a seald system.
Rich
Rich, Fern, Bethany, Justin. 2005 Ford F450,Lariat, 6.0 PSD,CC,DWR,4WD, Air Hitch, 100 Gallon Aux fuel tank.
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pirogue
lafitte la
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Joined: 09/30/2005
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I'm having the same problem with my duo therm. Neither of the copper line's are cooling, except capilary line(tiny) is really cold. I did notice my filter was folded and exposed the cold coils to be contaminated with dust.
I had an AC man come out and tell me the capillary line probably had been blocked and would need to be replaced????
It started raining on me today while I was up there cleaning the hot coils and was unable to open the cold coil side?????
Any suggestions? Does this guy Know what he's talking about?
Recap: Everything seems to be running in my unit just no cold air
Thanks
Craig 6/75, Tanya 6/78, Matt 5/03, Lane 2/06
F250 srw cc 4x4 psd
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quabillion
Fulltime Native Texan
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Joined: 08/20/2008
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First, I want to say that I make my living fixing air conditioners.
From what you describe, the valves in the head of the compressor are broken. An AMP draw reading will confirm this. If left running this way the compressor will overheat and shut off with the thermal cutout. If this is indeed the case, then your A/C is junk and should be replaced. The cost of replacing the compressor will be the same if not more money than a whole new A/C unit.
If the cap tube has plugged then there is some kind of "trash" in the system. Very hard to get it ALL out. And again very expensive.
* This post was
edited 09/02/08 01:02pm by quabillion *
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Bob Landry
Austin, texas
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Joined: 12/11/2005
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You are not going to be able to diagnose it without putting an amprobe on it. There is a current rating on the manufacturers data plate that will tell you what the compressor current draw should be. This will vary some depending on the ambient temperature around the unit, but it will be close enough for this diagnosis. If the draw is very low, the compressor is damaged internally even though it is running. A cap tube blockage will cause the unit to pull itself into a vacuum, and you won't know that unless you tap into the suction line and put a guage on it. Then you still have to repair the tap and recharge if you are going to repair the unit. I replace cap tubes and strainers all the time in marine systems, and it's easy to do, but a RV shop will hammer you on labor because you have to evacuate, replace, vacuum, and recharge = time, =$$$. When I do a compressor change on one of the marine units, the bill is over $900. It's far cheaper to replace the Coleman and Durotherm units if they are out of warranty..
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pirogue
lafitte la
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Joined: 09/30/2005
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Thanks alot guys! any suggestions on replacement brand and model.
Current model is a 620426.321
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pirogue
lafitte la
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are they easy to replace? I may try to do it myself since I have Been evacuated due to Gustav and do not want to pay for install and don't have time to wait. I'm fairly mechanically inclined. What do you guys think.
thanks again.
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quabillion
Fulltime Native Texan
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pirogue wrote:are they easy to replace? I may try to do it myself since I have Been evacuated due to Gustav and do not want to pay for install and don't have time to wait. I'm fairly mechanically inclined. What do you guys think.
thanks again.
the hardest part is getting the new one up onto the roof. If you like, just shove the old one off the side of the rig, laugh when it goes CRUNCH on the ground, and get 2-3 buddies to help lift the new one up there. Perhaps while standing in the truck bed. All the rest of the work is inside the rig.
I use my crane to lift A/Cs on and off a rig, but I do this for a living, by myself, so I kinda NEED the crane. Plus its about as handy as a front pocket on a shirt. Saved my sore back many a'time.
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