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Diemaker1 · 12-12-2019, 06:57 PM

Hi guys,

im having a issue were my 2 back roof top units are going into heat pump mode after running for 2-4 min. I reset my thermostats there due-therm. this did nothing I then switched and reset my other thermostat and the same thing. this all happened in the same day so I doubt theres an issue with the actual roof top unit as they do run in ac mode for a few minutes.

Any thoughts on this

I have a 2007 Monico 3 roof top unit

windsorbill · 12-13-2019, 07:39 AM

Quote:

Originally Posted by Diemaker1

Hi guys,

im having a issue were my 2 back roof top units are going into heat pump mode after running for 2-4 min. I reset my thermostats there due-therm. this did nothing I then switched and reset my other thermostat and the same thing. this all happened in the same day so I doubt theres an issue with the actual roof top unit as they do run in ac mode for a few minutes.

Any thoughts on this

I have a 2007 Monico 3 roof top unit

That's a classic symptom of the reversing valve solenoid failing. The older air/heat pump units default to 'heat'. You can try taking a strong magnetic up on the roof unit and using it in place of the solenoid. (or swapping the suspect solenoid with the one that seems to be working up front).

Having 2 solenoids fail at the same time, however, seems odd.

Diemaker1 · 12-13-2019, 08:50 AM

Quote:

Originally Posted by windsorbill

That's a classic symptom of the reversing valve solenoid failing. The older air/heat pump units default to 'heat'. You can try taking a strong magnetic up on the roof unit and using it in place of the solenoid. (or swapping the suspect solenoid with the one that seems to be working up front).

Having 2 solenoids fail at the same time, however, seems odd.

In thought that valve as well but find it strange they both went at the same time I will give that a try

windsorbill · 12-13-2019, 10:00 AM

Quote:

Originally Posted by Diemaker1

In thought that valve as well but find it strange they both went at the same time I will give that a try

I just realized it Friday the 13th.

8.3Oilbuner · 12-13-2019, 10:29 AM

Good morning Diemaker1; Yes as Bill mentioned, Friday the 13th! I also agree with Bill that both reversing solenoids on 2 units at the same time, strange. Although I have not had the problem you described, I was wondering about a communication problem with phone jack connections that plug into the roof A/C unit itself. Could those connections loose the A/C signal from the thermostat at the A/C unit itself and default to heat pump mode? Just a thought. I would unplug and plug back in the phone jack connections at the units involved and see what happens. Again, just a thought. Hope you find the problem and let us know the solution. Have a great weekend!

Timaz · 12-18-2019, 12:12 PM

Another cause can be "dirty 12 volt power" Put a 12 volt automotive filter just before it goes in the A/C...happened to me.

Diemaker1 · 12-23-2019, 05:20 PM

thanks guys when I get back to the unit I will check those items out and let everyone know

Outbound · 12-23-2019, 07:35 PM

Reversing valve would be my first choice.

Happycarz · 12-23-2019, 11:00 PM

You may want to reset the thermostat. This procedure is for a Dometic Comfort Control Center 5 button thermostat.

1. Turn the ON/OFF switch to the "OFF" position.

2. Simultaneously depress and hold the MODE and ZONE push-buttons while turning the ON/OFF switch to "ON". FF should appear in LCD display until the mode and zone push-buttons are released.

Diemaker1 · 01-17-2020, 04:10 PM

ok got the issue solved the starter cap was cooked on one of the units and the freeze sensor was shot on the other unit causing the unit to go into defrost mode
glad that mess is over