Airconditioning question

[Motor31]

For those that have had this happen I have a question about the compressor burning out.

What is happening now is that the blower is on just fine. INstead of the compressor coming on there is a loud hum and the lights dim a bit then the hum cuts off allowing the lights to go bright again (110 volt lamp). The air does not get cool and this cycle repeats about a minute later. To me it seems the compressor is fried but I wanted to check and see if the symptom is similar to what you have experianced.

 

[billr-5TH]

Mike,

It sure could be a Comp, you may have done this already, just check the power to see you have 110-120V while it tries to start. Just to be sure it's not Browning out. If the voltage drops too low the same will happen.

Cheers,
Bill

 

[Hobo-5TH]

Having been in the business I would say the compressor is locked up. 95% of the time that what it is but could be a starting compositor is bad.
Rick

 

[Motor31]

I checked the voltage, we're good there. I also tried letting it sit a while and see if cooling down opened it up, no dice. I also tried running it as a heat pump thinking possibly it had a coolant lock and reversing the flow might unblock it. That didn't work either and we started to get a hot wire smell so it's off line except for the blower to help move air from the bedroom unit to the rest of the trailer.

We're in Lafayette LA now and last year Dometic / Duotherm was less than stellar on getting service in this area on the unit for failure to operate properly in the heat pump mode by switching over to the furnace. When we went to the factory for sevice last May they ended up swapping out this same unit. Now it's 11 months later and it's belly up. sigh. Here we go again.

 

[jdwilson3]

AC

Mike, our front (BR) 13.5 AC had the compressor sieze, when the unit was only 2 months old.

Dometic replaced the unit, with no hassles. When I told the mobile RV Technician over the phone the symptoms, he called Dometic, had the new unit in a few days, and did the replacement.

If your unit is "older", Dometic may have the compressor replaced instead of replacing the whole unit.

 

[Motor31]

Whelp, it's solved.

The compressor was fine. It was the "start up capacitor" that fried. It was most definitely toasted and took out the wiring leading to and from it. The burning stopped short of the board but a couple inches or wire had to be cut off and new connectors replaced. The capacitor got hot, really hot to the point it looked like the top had actually been on fire and that heat burned up the wiring insulation on the connecting wires. It took 15 minutes for the repair once the tech got on it. This is on the main AC / heat pump unit that was replaced last May.

I went to the place I found on the Dometic web site on my bike first to make sure that I could fit in the shop area and that the work would be authorized before packing up and getting the rig there. It was a good call to not just bring the rig. They do work on some Dometic products but noting related to freon or refridgerators. They did give me two numbers and names of folks who did do AC work. Both also did work at your location. One was on the factory authorized list so I called them. He was there in 2 hours and gone in 2.5 hours. The repair was covered but I did pay for the onsite visit. To me it was worth it given I'm at our son's place to help them pack and move. (I supervise a lot with my back) They have full hookups for us but getting in and out is a pain with the construction.

That was one situation. To make things even worse I had two other failures in the rig. When I dumped the tanks I tried to flush the black tank as usual. The check valve locked up and no water was able to pass into the tank. Then the water fitting blew the hose off stripping the threads in the fitting. I also got soaked since I was working the dump valve at the time. That was Thursday night.

Oh joy, Friday the 13th is such a wonderful thing....... I went to 3 RV supply locations before I could find replacements for each but got them both at the third supply house. It was only 50 miles of driving in heavy traffic on a Friday.. on a motorcycle..........

I did the repairs in 30 minutes and was able to go "supervise" some more before calling it a day. Now we have thunderstorms with possible heavy hail due late tonight then tomorrow. Sigh.

 

[Motor31]

It seems the elation over the AC situation was premature. This afternoon the main AC unit is doing the same thing again. While I am not yet smelling the burning wiring, the cyclic hum and incomplete cooling is happening all over again. Just in time for the increase in temperature and humidity.

 

[Motor31]

The AC is back in operation, for now. The latest failure was in a small electrical component labeled "motor starter". This thing is the size of a larger postage stamp and about a 1/4" thick with two wire connectors. It was rather "crispy".

While there, the tech did some extensive diagnostic tests and found the compressor was drawing more than it's rated amperage for the temperature. It was 75 degrees outside and the compressor was drawing the maximum number of amps for a 95 degree temperature. The tech wanted to swap out the unit figuring the compressor will fail fairly soon. Dometic refused even though the unit is beyond their own factory specs. I expect to have to deal with this again before too long.

If you get a moderate to strong hot electrical smell while running your AC unit be prepared to call for service. Chances are it may be either the large capacitor or the starter motor device. If it's the capacitor is does burn wires attatched to it.

 

[Hobo-5TH]

While there, the tech did some extensive diagnostic tests and found the compressor was drawing more than it's rated amperage for the temperature. It was 75 degrees outside and the compressor was drawing the maximum number of amps for a 95 degree temperature. The tech wanted to swap out the unit figuring the compressor will fail fairly soon. Dometic refused even though the unit is beyond their own factory specs. I expect to have to deal with this again before too long.

Motor31,, Both the capacitor and start relay going bad are signs of the compressor having a hard time starting and drawing too many Amp in the proses. Your correct in thinking it won't make it though the summer. I hope your staying some place that includes electric as your power draw will be up as long as it keeps going.