Faulty heat pump thermostat?

[fergo27]

I have a 2005 Win Journey that has an RVProducts Heat Pump. It uses a True Air Coleman-Mach thermostat. I'm guessing maybe my thermostat has gone south. On a recent trip, my heating and air were working properly. After shutting it down, the next time I tried the heating (either gas or electric) it would not turn on. The airconditioning portion works fine. Also, the switch for the fan, which says "auto" or "on," when put in the "on" position it will not run. I've checked the two circuit breakers and the 2amp fuse within the thermostat, all seem to be good. I know the thermostat (board with switches) is easy to remove. Anybody have any suggestions?

[LandKinaMoho]

Detatch and clean with an electronic cleaner spray.

[ernieh]

What LKM said, plus see if it still doesn't work with the fluorescent (ThinLites) off.

Also, remember that the ON position for the fan only works if the thermostat is selected to OFF or COOL.

[hdmoxness]

Originally Posted by fergo27

...the switch for the fan, which says "auto" or "on," when put in the "on" position it will not run.

Normal operation for my coach: the fan will only respond to the "on" position when the 4-position thermostat slide switch is in the "off" position. It is for when you want to run the fan only and is the fan that blows air from the overhead vents.

[DAN L]

Originally Posted by fergo27

I have a 2005 Win Journey that has an RVProducts Heat Pump. It uses a True Air Coleman-Mach thermostat. I'm guessing maybe my thermostat has gone south. On a recent trip, my heating and air were working properly. After shutting it down, the next time I tried the heating (either gas or electric) it would not turn on. The airconditioning portion works fine. Also, the switch for the fan, which says "auto" or "on," when put in the "on" position it will not run. I've checked the two circuit breakers and the 2amp fuse within the thermostat, all seem to be good. I know the thermostat (board with switches) is easy to remove. Anybody have any suggestions?

check the relays and capacitors on the electrical panel under the ac-heat pump louvered door. on my moho the door is secured by a screw in the rear and another in the front. the louvered door hinges up.

[Duner]

Neil & Rilla,

My Coleman Mach thermostat started acting up in year two. I had trouble with the slide switch. The mode switch is actually two slide switches ganged together. As they wear they get loose and can put the a/c heat pump into invalid switch positions.

You may be able to determine if it's the switches in the thermostat by tweaking and doing a fine adjustment to the switch positions. Then if you can get it to work temporarily it pretty much points to the switch problem.

I'm an electronic guy so I didn't hesitate to go inside and tighten up the slide switches with long nose pliers. And that worked for about another year. I my opinion, the plastic mechinism is a design defect since I have read about so many 'stat problems thru the years on this forum.

If you decide the stat needs replacing, in the last few months, some of the members have found the Coleman for around $110. Search the threads here to find where they got the good price. I replaced mine with a digital touch screen from Home Depot for about $75(RiteTemp 8085C) and it has been working fine for over 6 yrs now. If I was putting in a new one today, I would choose this Honeywell from Home Depot. It has very high ratings by 24 user reviews. The wiring connections use industry standard labeling and you can download the wiring conversion chart that I have on my website (see my signature below for the link).

Good Luck,
Bill

[fergo27]

Bill,

Thanks so much for your insight (and experience). I'll definitely look into the info you gave me. I, too, suspected the slide switch. I sprayed all of them with an approved cleaner. They definitely had more of a positive feel, but, alas, still didn't do the job. Another glitch is that the fan switch does not turn on the fan in the "on" position. And I realize the heat and air have to be in the "off" position. Per your suggestion, I'll look into the Honeywell system. Thanks again.

Neil

[MaxTurner1]

I have a 2005 Adventurer with the basement HVAC. The Tru-Air thermostat seems to have about a four degree span between set and actual. Is there a way to tighten up the span?

[fergo27]

Thanks to all who offered advice for my problem. It's still a work in progress, but I'm hopeful, with your help, I'll be able to fix it. Thanks again.

Neil

[Duner]

Originally Posted by MaxTurner1

I have a 2005 Adventurer with the basement HVAC. The Tru-Air thermostat seems to have about a four degree span between set and actual. Is there a way to tighten up the span?

Sorry Max, I just checked my old Coleman Mach and there's no adjustment. The only internal option is to display F or C units.

I looked at my RiteTemp and it defaults to 3 deg swing. From the touch screen I can change it down to 2 or 1 deg, or up to 4 or 5 deg swing.
Another option I have is to put in an offset temp which would compensate for a temp difference between stat location and where you normally spend your time, say up front closer to the windshield where it is colder.
Lots of features in the new electronic stats..... like a filter timer that tracks how many hours on the filter, then it will set a flag to remind you to change it out or clean it.

Take care,
Bill

[MaxTurner1]

Thanks Bill,
Looks like I want a RiteTemp. Next question --- since we three options, (cool, gas heat and electric heat), how do you handle that?

[DAN L]

Originally Posted by MaxTurner1

Thanks Bill,
Looks like I want a RiteTemp. Next question --- since we three options, (cool, gas heat and electric heat), how do you handle that?

check bill e.'s website.

bill&helen2010

[NoMoreAZ]

Originally Posted by Duner

If you decide the stat needs replacing, in the last few months, some of the members have found the Coleman for around $110. Search the threads here to find where they got the good price. I replaced mine with a digital touch screen from Home Depot for about $75(RiteTemp 8085C) and it has been working fine for over 6 yrs now. If I was putting in a new one today, I would choose this Honeywell from Home Depot. It has very high ratings by 24 user reviews. The wiring connections use industry standard labeling and you can download the wiring conversion chart that I have on my website (see my signature below for the link).

Good Luck,
Bill

Dune'r,

The Honeywell Thermostat referenced above operates on 24 volt or 750 mV systems. No 12 VDC. No AC.

Got this info from page 11 of the Install Guide for the product. Install Guide does not supply a schematic. I am also looking for a replacement for our Coleman-Mach.

[Duner]

Originally Posted by NoMoreAZ

Dune'r,

The Honeywell Thermostat referenced above operates on 24 volt or 750 mV systems. No 12 VDC. No AC.

Got this info from page 11 of the Install Guide for the product. Install Guide does not supply a schematic. I am also looking for a replacement for our Coleman-Mach.

My RiteTemp runs on two AA batteries and provides contact closures to switch the +12v signals. If the Honeywell works for millivolt controls, then it too runs on batteries for the electronics and uses contact closures to the furnance /AC unit. This is my educated guess and needs to be verified.

[NoMoreAZ]

I probably should have been more specific in my last post. The 24 volts referred to is the 24 VAC that is usually found in residential or commericial HVAC systems. This 24 VAC comes from a transfomer in the HVAC unit. Honeywell said no 120/240 VAC. Most current product line thermostats use 2 AA batteries; the one referred to (Honeywell RTH7600D) does. This thermostat has various wiring options (contact closures) for a heat pump.

Our coach has two gas furnaces. I replaced the cheap thermostat that 'Bago used for the bedroom furnace with a Honeywell RTH 110B four years ago. Basic two wire system to control the furnace. Works great, has digital readout, accurate, much better than previous unit with analog scale with 10 degree separations.

[oldpals]

Originally Posted by Duner

Neil & Rilla,

My Coleman Mach thermostat started acting up in year two. I had trouble with the slide switch. The mode switch is actually two slide switches ganged together. As they wear they get loose and can put the a/c heat pump into invalid switch positions.

You may be able to determine if it's the switches in the thermostat by tweaking and doing a fine adjustment to the switch positions. Then if you can get it to work temporarily it pretty much points to the switch problem.

I'm an electronic guy so I didn't hesitate to go inside and tighten up the slide switches with long nose pliers. And that worked for about another year. I my opinion, the plastic mechinism is a design defect since I have read about so many 'stat problems thru the years on this forum.

If you decide the stat needs replacing, in the last few months, some of the members have found the Coleman for around $110. Search the threads here to find where they got the good price. I replaced mine with a digital touch screen from Home Depot for about $75(RiteTemp 8085C) and it has been working fine for over 6 yrs now. If I was putting in a new one today, I would choose this Honeywell from Home Depot. It has very high ratings by 24 user reviews. The wiring connections use industry standard labeling and you can download the wiring conversion chart that I have on my website (see my signature below for the link).

Good Luck,
Bill

Hey Bill.......thanks for the info and the link to your site for the wiring conversion. Since the only one I found there was for the Rite Temp I assume that they are wired the same way. The honeywell has the jumper
between RC & R.....not RC & RH. So do I just leave this jumper in then?
And by just turning off the battery switch and not being connected to AC can I install without blowing something up?
Thanks.......Linda

[Duner]

Originally Posted by oldpals

Hey Bill.......thanks for the info and the link to your site for the wiring conversion. Since the only one I found there was for the Rite Temp I assume that they are wired the same way. The honeywell has the jumper
between RC & R.....not RC & RH. So do I just leave this jumper in then?
And by just turning off the battery switch and not being connected to AC can I install without blowing something up?
Thanks.......Linda

Sorry I couldn't get back to you sooner, we were out in the motorhome in the mountains behind Santa Barbara with no internet.

Ya, the markings on the terminals are industry standard. It's been too many years since I figured out what each wire controls, so I can't give you an answer without getting into the manuals. I'll spend some time on what the jumpers do and get back to the thread here.

Bill

[dvleemin]

I'm assuming that changing over to the Honeywell that you lose the ability to have a high/low fan speed setting?

[Duner]

Originally Posted by dvleemin

I'm assuming that changing over to the Honeywell that you lose the ability to have a high/low fan speed setting?

Yes, you will only have one speed (hi). But if you really like to have the low speed too, just add a small toggle switch somewhere convenient. Many of us have already decided that there is too little difference in speeds, that is low is not very low, so having hi speed only is just fine.

[dvleemin]

Originally Posted by Duner

Yes, you will only have one speed (hi). But if you really like to have the low speed too, just add a small toggle switch somewhere convenient. Many of us have already decided that there is too little difference in speeds, that is low is not very low, so having hi speed only is just fine.

Thanks.

What model of thermostat did you use as a replacement?