Another Coleman off roof AC question

[HD4Mark]

My neighbor who is in HVAC hasn't got back to me yet, I'm sure he is busy since it has been in the 90's here, so I will post the events so far here and see if anyone has had this problem.

It is a Coleman Mach Two Ton 6535 like in many MH's and stopped cooling last March. I pulled it out myself, cleaned the coils and oiled the blower motors. He had one of his guys check it out, no leaks but for whatever reason he thought the R22 was a little low so he topped it up. After that the condenser coil would sweat all the way up rather than about half way. Then he noticed that after 15 min running and sucking in 92 deg air (remember it is not connected to the ducts and pulling outside air) the second compressor quit. He thought it might be a sensor that is stuck into the condenser coil, can't remember what he called it but it is to prevent it from freezing so he disconnected it. Saturday I slid it back in and let it run all night then after it got warm out yesterday checked it, 81 deg inside and only one compressor was running.

The second compressor fires right up after the normal delay so it is working but something is shutting it down before it is cool enough. I think from the parts list the thing he disconnected is called a 7330A3231 Coil Sensor. Make sense to anyone?

[TXiceman]

I think you need to find someone more knowledgable than your neighbor. He is getting into an area that he has no knowledge and may eventually find the problem by a chage parts approach.

Ken

[RV Wizard]

Sounds like the unit is operating properly. What temperature did you have the thermostat set at? When only 1 compressor is needed; temperature of room is close to set point. If you have more that a couple of degrees difference then the second compressor should be online.

[HD4Mark]

Quote:

Originally Posted by RV Wizard Sounds like the unit is operating properly. What temperature did you have the thermostat set at? When only 1 compressor is needed; temperature of room is close to set point. If you have more that a couple of degrees difference then the second compressor should be online.

The temp was set at 72, room temp 81. The power center only read 14amp draw is the only reason I even noticed the second compressor was not running. The MH is plugged into a 30A outlet I installed on our garage, the house entrance for power. When the second one does fire up it reads 28 or 29.

Quote:

Originally Posted by TXiceman I think you need to find someone more knowledgable than your neighbor. He is getting into an area that he has no knowledge and may eventually find the problem by a change parts approach. Ken

His grandfather started the company making bar/restaurant coolers. He told me the guy he sent was one of their sharpest guys. I am pretty sure that if it is outside of what they know he will tell me so. They are also kind enough to let me do as much of the work as I can handle. I don't think many HVAC guys would be too willing to do that.

I did look up Coleman authorized AC service on their web site that are close to us. One we had never heard of the other we aren't thrilled with because a few years ago when we still commuted to work we saw one of that companies truck almost every morning and the guy drove like a jerk, speeding and cutting people off. I know it was just one employee but things like that leave a bad impression.

[Dave78Chief]

Here is a link to the service manual. Hopefully that will help you isolate your problem
Dave

http://www.rvcomfort.com/pdf_documen...6323_copy8.pdf

[HD4Mark]

Quote:

Originally Posted by Dave78Chief Here is a link to the service manual. Hopefully that will help you isolate your problem Dave http://www.rvcomfort.com/pdf_documen...6323_copy8.pdf

Thanks for the link. I have that and sent it to my neighbor friend, he printed it and the parts list for his tech. I don't want to rush them since it was really hot here and I bet they have enough to do plus we only use the MH in the fall to spring to escape the weather here. I have three months or so before we go.

If it comes right down to it we will buy a new unit but I understand they are 50amp only. Once in a while we will stay at a CG that doesn't have it so it would be better to fix ours.

[RV Wizard]

Tech needs to diagnose when the compressor drops out as to it being a control signal opening contactor to compressor or not. Good luck and keep us posted.
Oh, btw, I think you are confusing condenser coil with evaporator coil in your original post.

[HD4Mark]

Quote:

Originally Posted by RV Wizard Oh, btw, I think you are confusing condenser coil with evaporator coil in your original post.

Your right Wiz and I always do that. Some kind of mental block like those words you can never spell right. To make matters worse I looked right at the exploded parts picture.

I talked to my neighbor last night and his guy must have done some research or had a light come on because he wants to look at it again. Thanks for the advice I will ask him about it.

[HD4Mark]

Update: This morning the ac tech strapped Y1 and Y2 on the thermostat. This forces both compressors to run. Started out at 83 inside and the best it could do was 75. Just checked an hour ago and up to 77. Outside temp is 82, sun and clouds with a nice breeze. This POS is getting frustrating.

[RV Wizard]

Ask him to check the control board. There is a couple of LEDs on it that will alert of some problems. Also while he is there have him check the amperage of the compressors at start up and when running for about 5 minuets. let us know what you find.

[jcthorne]

Are you sure its not your EMS shutting down the second compressor? Thats exactly what its supposed to do on 30 amp service if ANY other load comes on. Your battery charger/converter is sufficient to cut out the second compressor when on 30 amp service.

[HD4Mark]

Quote:

Originally Posted by jcthorne Are you sure its not your EMS shutting down the second compressor? Thats exactly what its supposed to do on 30 amp service if ANY other load comes on. Your battery charger/converter is sufficient to cut out the second compressor when on 30 amp service.

Never thought of that. The only thing running is the AC and the charger. It is parked at the house so we turned everything off but the AC to test it. he EMS reads 21 or 22A draw with both running. Would the second compressor come back on after the inverter/charger was done?

I really need to change the 30A to a 50A outlet. It's only about 20' from the entrance and breaker panel.

[jcthorne]

Its supposed to come back. EMS systems are always the first system I question as they are know for being flakey. I would try a 50a connection or with the gen set running and see if the two compressers stay running.

The EMS systems seem to think you are using more power than you are and shed load when they don't need or don't bring load back.

[HD4Mark]

Looks like it has come down to the thermostat. First it reads way off. 67 with HVAC guys thermometer 72 on thermostat readout. Both compressors ran with the Y1 and Y2 strapped so he is thinking the second one cutting out may be the thermostat also.

I am sure the filthy coils, the evaporator coil was very dirty and deteriorated foam seals on the unit didn't help either. While we changed the filter often, who knows what PO did. Topped up with freon and the blower bearings lubricated I'm hoping we will be set to go.

Now I am looking into replacing the Coleman thermostat with a home type 2 stage heat pump model. See here TrueAir thermostat replacement revisited It is not as easy as you would think.