Roof A/C's Dead

[IdahoPoes]

I recently swapped out the analog Coleman-Mach thermostats with digital ones. I made sure the wiring on the thermostats matched the old ones. Now the roof A/C's will not come on. No compressor or fan in either one. The A/C circuit breakers are both on and not tripped. I hear the relays in the thermostats click and they report 'COOL ON" steady on both but nothing out of the A/C's.


Are there reset switches someone I am not aware of?


Any help appreciated!


Marshall

[Ron1Z]

No reset that im aware of. Double check your wiring, im assuming that you have the correct thermostat 1 stage heat 1 stage cool. Try touching red wire to yellow wire with power on the fan should come on, maybe a bad stat?

[safari]

Originally Posted by IdahoPoes

I recently swapped out the analog Coleman-Mach thermostats with digital ones. I made sure the wiring on the thermostats matched the old ones. Now the roof A/C's will not come on. No compressor or fan in either one. The A/C circuit breakers are both on and not tripped. I hear the relays in the thermostats click and they report 'COOL ON" steady on both but nothing out of the A/C's.


Are there reset switches someone I am not aware of?


Any help appreciated!


Marshall

Please keep us updated on the fix.
& the pros & cons after you get it working.

Good luck.

[IdahoPoes]

Originally Posted by Ron1Z

No reset that im aware of. Double check your wiring, im assuming that you have the correct thermostat 1 stage heat 1 stage cool. Try touching red wire to yellow wire with power on the fan should come on, maybe a bad stat?

Thanks!! I'll give the jumping red to yellow a try. If bad thermostat then it would be two of them (front AC and rear AC separate thermostats - both changed).

[IdahoPoes]

Originally Posted by safari

Please keep us updated on the fix.
& the pros & cons after you get it working.

Good luck.

Will do!

[IdahoPoes]

Jumper red and yellow together did not cause the fan to come on. I know the thermostats are good because I hear them clicking when set to cool.


Decided to look at 12V fuses. One labeled 'Appliances' (15 A). Checked it and it was blown. I replaced the fuse and all is well now.


Thanks for the tip on isolating the thermostat - that caused me to check the 12V angle.


Both thermostats now digital with a very narrow temperature swing.


Marshall

[Bob Denman]

Congratulations!
How does it feel to be one of "The Cool Kids"?

[javelin]

Use a voltmeter and check that red (RH/RC/R terminal or whatever is used on thermostat) has +12vdc on it.....also depending on the thermo the RH and RC terminals should be jumpered together if they are separate terminals)......so if touching the RC terminal to Y terminal (which is for cooling compressor) and there is no joy......try checking that the blue (B) is grounded on the thermostat. If the thermo has its own batteries then what used to terminate on the B terminal of the old analog thermos (coach ground) has to still provide ground to the relay in the air conditioning control box......usually accessible by removing the inside ceiling escutcheon vent panel of each air conditioner if you need to get in there. Check the wiring behind the thermo first though. The fact that both air conditioners and two new thermostats are doing the same thing.....means the trouble is probably the common denominator......the person wiring missed some little thing I suspect. Maybe?

[javelin]

oops missed the "part about you fixed it already".....I'll just go back to sleep then.

[Mo_Mike]

Originally Posted by IdahoPoes

Jumper red and yellow together did not cause the fan to come on. I know the thermostats are good because I hear them clicking when set to cool.


Decided to look at 12V fuses. One labeled 'Appliances' (15 A). Checked it and it was blown. I replaced the fuse and all is well now.


Thanks for the tip on isolating the thermostat - that caused me to check the 12V angle.


Both thermostats now digital with a very narrow temperature swing.


Marshall

We replaced our analog with a digital over a year ago. No comparison. The temperature range is now within a degree or two (makes sleeping MUCH more enjoyable instead of the "sweating and freezing" saga of the analog unit)

Definitely a worthwhile upgrade!

[safari]

Originally Posted by IdahoPoes

Jumper red and yellow together did not cause the fan to come on. I know the thermostats are good because I hear them clicking when set to cool.


Decided to look at 12V fuses. One labeled 'Appliances' (15 A). Checked it and it was blown. I replaced the fuse and all is well now.


Thanks for the tip on isolating the thermostat - that caused me to check the 12V angle.


Both thermostats now digital with a very narrow temperature swing.


Marshall

Great,Good for you.