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-   -   Help my outside unit is not working (http://www.diychatroom.com/f17/help-my-outside-unit-not-working-77337/)

lhaviland 07-28-2010 09:36 AM

Help my outside unit is not working
 
My outside unit will not come one. I have recentky changed the run cap, the contactor, and the thermostat; however I'm afraid the thermstat may not be wired right. The problems started a week ago .first the ac went out in the middle of the night, was out the entire next day until we flipped all beakers and then it came on it worked fine until Friday when we turned the old therm up the unit kicked off and would not come back the entire day. So the next day we tried the breakers and nothing happened, a little while later the outside unit came on but this time it ran for 24 hours straight, so we turned it up again b/cthe therm was set on 76 but the temp was now down to 68. This was the last time it worked I have since switched all of the above listed componants but I'm not sure if the therm is wired correctly. The inside fan works fine. Carrier Tech 2000SS model#38TRA024320. Thanks
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hennyh 07-28-2010 11:20 AM

If it's an existing installation that had previously been working then why do you think the thermostat wiring is wrong??

If the unit is dead and then comes back on after cycling the circuit breaker then you could be resetting it's internal protection circuitry like lo and hi pressure lockouts. Ambient temperature variance could be affecting pressures enough to trigger lockout at certain times during the day. (low pressure lockout when cool, high pressure lockout when hot)

The thermostat is typically the most reliable component in an HVAC system but many homeowners and techs. immediately think it's at fault.

You said you replaced contactor and capacitor. I'd be checking if it's shutting down to try and protect itself from abnormal pressures.

I think you've done what you could and are now a candidate for getting a good tech. to help out.

lhaviland 07-28-2010 01:34 PM

Thank you for responding.

We changed the thermostat last night b/c we'd changed the run cap the day before and there was no change. Someone suggested that it may be the thermostat, so we purchased a universal thermostat. However, with a universal one there are several different configurations that it could be. I'm pretty sure that we have a heat pump as that is pretty common for houses in FL, but how can I be sure?

In my last post I failed to mention that the few times the outside unit did come we had lowered the temperature on the tstat to 68 deg. Could this mean that it was something was wrong with the tstat?

Thank you!

hennyh 07-28-2010 02:02 PM

Quote:

Originally Posted by lhaviland (Post 476759)
We changed the thermostat last night b/c we'd changed the run cap the day before and there was no change. Someone suggested that it may be the thermostat, so we purchased a universal thermostat.

Sorry to be blunt, but that's a crappy way to troubleshoot!!

Randomly replacing new parts in hope that you get lucky and find the culprit is rediculous. Now you just introduced 3 new variables which will impede your ability to narrow down the problem.

(ex: not only do you have a malfunctioning system, but now you may have a malfunctioning system with a suspect thermostat.)

Although this forum is DIY, this is a good time to seek out help from the pros. A HP can be controlled via jumper wires at the control board which will simulate the operation of the thermostat. That's a better way of determining if the problem is related to the thermostats ability to control the system.


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