air conditioner trouble

[skipper13]

My front air will not cool. It is a dometic that was bought new from CW 5 years ago. Fan works but compressor will not cycle on. Anyone have any ideals on what is wrong and how to fix without getting another new unit.

Thanks

[Chris_Bryant]

skipper13 wrote:

Chris Bryant wrote:
Could be a number of things- what kind of thermostat does it use?

It has a hunter tstat

So, it has the older analog controls- it could be the thermostat, thermostat wire, control board, freeze sensor or something on the roof unit.

First, with the upper unit plugged in and the thermostat calling for cool, I would check for 120 volts between the white and blue wires coming out of the control box- or if you want to unplug the upper unit, you must use a test light. If you do have 120 volts here (or it lights the light), the problem is in the upper unit, if not, the problem is controls.

The freeze sensor in this model is a simply switch- should be open at normal temps (closes near freezing, which shuts down the compressor).

Last would be to short the yellow thermostat lead to ground, which will energize the compressor relay.

[skipper13]

smkettner wrote:

skipper13 wrote:
My front air will not cool. It is a dometic that was bought new from CW 5 years ago. Fan works but compressor will not cycle on. Anyone have any ideals on what is wrong and how to fix without getting another new unit.

Thanks

Any chance you have an energy management system restricting power?

No energy management system. Hooked to 50 amp service

[skipper13]

Chris Bryant wrote:
Could be a number of things- what kind of thermostat does it use?

It has a hunter tstat

[time2roll]

skipper13 wrote:
My front air will not cool. It is a dometic that was bought new from CW 5 years ago. Fan works but compressor will not cycle on. Anyone have any ideals on what is wrong and how to fix without getting another new unit.

Thanks

Any chance you have an energy management system restricting power?

[dougrainer]

Robert78121 wrote:

dougrainer wrote:

Vet Man wrote:
Could need to be charged.

If so, the compressor would still come on. Doug

I thought these units had a low/high pressure cutoff switch, so I'm not sure that's entirely true.

Well lets see. I am a Master Certified RV technician and have been a RV technician for 34 years. I have extensive training by both RVP (Coleman) and Dometic, the major Makers of RV AC units.
NO roof top RV AC unit has any type pressure switch and have not since at least 1974. Doug

[BruceMc]

Sounds like the starting capacitor may be bad. Search this site for start capacitors... There's been several postings recently on this topic.

[Robert78121]

dougrainer wrote:

Vet Man wrote:
Could need to be charged.

If so, the compressor would still come on. Doug

I thought these units had a low/high pressure cutoff switch, so I'm not sure that's entirely true.

[dougrainer]

Vet Man wrote:
Could need to be charged.

If so, the compressor would still come on. Doug

[Vet_Man]

Could need to be charged.

[Chris_Bryant]

Could be a number of things- what kind of thermostat does it use?