Thermostat Reading Outside Temperature After Cleaning Roof A/C Cleaned

[greenbarn1]

Had Coleman (rvp) roof air a/c cleaned yesterday. After cleaning zone 2 is reading outside air temp. Thermostat is Atwood 4 button.

Swapped thermomister from zone 1 same result. Checked all connections all looks OK. Mobile RV service who did cleaning said maybe a control board.

Thermostat controls furnace, heat pump and a/c.

Coach is 2004 American tradition 2 rooftop air conditioners.

[huffypuff]

I believe that resetting the thermostat is worth a try. It was on a recent thread.

http://community.fmca.com/topic/7898-roof-ac-shuts-off-when-compressor-starts/?hl=reset#entry50830

[greenbarn1]

Thanks for reply. I did reset thermostat to factory settings. Zone two continues to read outside temp. At Lazy Days today have appointment on the 9th.

I was hoping someone had come across this. I noticed thermistor in zone two had been replaced before.

I am second owner 1st owner had coach serviced only at Fleetwood in Decatur.

[campcop]

I think it's sort of odd that right after the tech services the unit it, the problem started.....makes you wonder just what he did up there..

[greenbarn1]

You and me both. Swears he moved control box to the side and cleaned coils. Said he's been in business along time and cleaned many a/c. Said if he did I'll pay. Just my luck every time something happens to me it's a first.

I was wondering if evaporator and thermostat plugs were switched would that be the problem?

[dickandlois]

Evaporator would be on a 25 to 30 amp circuit and the thermostat would require much less current. Think the wire gauge and connector sizes would be different sizes also.

Rich.

[greenbarn1]

I was thinking of probe inserted in evaporator in case evaporator freezes it shuts down compressor. Maybe that connection and thermometer got switched

[gbrinck]

The thermostat isn't connected to any of those sensors in the a/c - its thermisters are inside the coach. The t-stat sends a control signal to the a/c circuit board and the a/c's own controller decides whether to run, whether coils are frozen, or whatever. It has no way to send outside air temp back to the thermostat.

I have the same coach, by the way.

[greenbarn1]

Thanks gbrinck for the reply. I don't know how but zone 2 on my atwood thermostat is absolutely reading outside air temp. When a/c is running on a 85 degree day I could set zone 1 and two at 76 degrees and both would read within 2 degrees of setting. Now zone two can read 74 degrees in the morning and by early afternoon zone two is reading 85 degrees or hotter. A/c is running in both zones and room temp is 76- 78 degrees in coach. Problem is zone 2 a/c will run all day because thermostat thinks that zone is very hot when in fact it is 76-78 degrees. I switched zone 1 and zone 2 thermistors and had same result.

[greenbarn1]

Just would like to add we put thermomister from zone 2 in ice cold water for over 5 minutes and thermostat still read 87 degrees today. Swapped thermomister from zone 1 which was reading 76 degrees as set on thermostat!!! and that one read 87 degrees. Put zone 2 thermomister on zone 1 and it read 76 degrees.

[greenbarn1]

Problem solved!!!! Thermistor for zone 2 was found unplugged. I don't know why first guy could not see that. Well lessen learned next time only mobil guy in a emergency. I know dealerships have some well earned reputations. but some time it's cheaper and easier to pay them once. Lazy days in Tampa gave me excellent service start to finish. Boy those are words I thought I would never say. They were EXCELLENT !!