Since I have owned this coach, I have not used rear AC much. But it always worked when I needed it; until last Saturday. I turned it on to cool, selected a lower temp and just had fan only. No compressor action. Thinking that this 28 year old AC unit was finished, I started looking for replacements. After reading some old posts, I decided to start some troubleshooting first. I turned it on today and climbed on roof (cover was removed and metal cover over control board was also removed). Fan was running fast and tru but no compressor. I took a screwdriver and tapped large Potter & Brumfield relay that fed start capacitor and clunk, the compressor engaged. I then suspected the relay was bad. I shut it down, and went back up to pull relay off control board. When I took my needle nose pliers and started wiggling the connector to remove the wire, the relay came right off the board. I took board into house and following inspection of board and relay, I soldered relay back on to board; checked all other soldered connections and went back outside. I reinstalled the board and fired it up. After 2 min programmed "warm up", compressor engaged and is working flawlessly. I measured a 50 degree output temp with ambient arounf 85 degrees. Probably saved about one coach buck and plan to ride this AC unit for the indefinite future.
Long story I know but the lesson is before junking something with a circuit board, check those soldered connections.
In photo, large relay at lower left was the culprit.
FWIW
jk
Excellent demonstration of trouble shooting skills! Congrats!
When you think about the abuse those old circuit boards take, both from the vibration of the compressor unit itself running, AND from bumping down thousands of miles of rough roads on top of the coach... Pretty amazing any of them still work, especially after almost 3 decades.
What is that 3 or 4 trips up on the roof for a CB savings. I don't know. You must be a younger man than I.
Good News, a lot of time poor connections, poor grounds cause a lot of problems. Bad capacitors are also a problem that are easily repaired. A good capacitance tester is not expensive and can save a lot of costly repairs.
Congratulation on your fix, I love those stories.
Safe Travels
Dave
It was three trips, Larry. At 71, I've decided I'll wear these old joints out rather than "rust away".
jk
That's the spirit! Use it or lose it. b^.^d
Anyway, yer still a youngster! At 74.5 years young, I can still scamper up and down our ladder like a monkey.
Since I don't bounce like I did back in the day, I AM careful when walking or working on the roof. So far, so good...
Here I thought all you guys were older than me!
I'll be 78 this coming Saturday. Managed to play softball until I was 64 and collected 16 MVP trophies along the way.
Now my body is demanding pay up time.
At 76 I've just had a shoulder replaced and am heading to one hip and both knees replaced yet this year. Too much "scampering" and thinking I was invincincible for too long. :help:
Ok, back to A.C. problem. My rear A.C. kicks on and off as it should, however the blower motor only runs when the compressor is running or when the fan switch is set to a specific speed or auto. The blower motor fan used to continue to run for a few minutes after the compressor shut down, to blow the cool surfaces of the evaporator, but it has stopped doing that. What would be the cause of that?
That would seem normal to me. The fans keep running on heaters after the burner shuts off, but I haven't had any that keep running after the cooling cycle stops. I don't know how all air conditioners work but all mine work this way.
Gerry said:
Ok, back to A.C. problem. My rear A.C. kicks on and off as it should, however the blower motor only runs when the compressor is running or when the fan switch is set to a specific speed or auto. The blower motor fan used to continue to run for a few minutes after the compressor shut down, to blow the cool surfaces of the evaporator, but it has stopped doing that. What would be the cause of that?
Both my AC's work as Craneman mentioned. Power off = fan off. If you are troubleshooting, the large relay that is 4th down in my photo, is the fan relay. It is on/off only, not latching.
jk
Relay is Potter-Brumfield T91S1D22-24
https://www.onlinecomponents.com/te-connectivity-p-b-brand/t91s1d2224-12114887.html?ref=searchads360feed&utm_term=T91S1D22-24&gclid=EAIaIQobChMIscSio6ys6gIVSrzACh0U8AIDEAAYASAAEgKaFvD_BwE&gclsrc=aw.ds