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Old 09-10-2011, 01:01 AM   #1
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AC shutting on and off...


Hey all...noob here.

Sorry for a long initial post, but here goes.

Got a little problem I'm trying to diagnose.

First off, a little about my background. I've been in the home performance testing industry for about 5 yrs now and test residential air delivery systems every day. I am by no means an HVAC professional, but am at least somewhat knowledgeable about how HVAC systems work and proper terminology.

The extent of my formal training is related to testing and diagnosing issues related to building envelope and duct system leakage, air flow balancing and static pressure testing, that's about it. I've never been involved in designing, installing or servicing HVAC systems.

My system is a +/- 15 y.o., horizontal attic mounted, Janitrol POS heat pump system on it's last leg with a new honeywell digital t-stat, which was installed last year. We've only lived in this house about 3 yrs and the system was horribly maintained by previous renters.

When we moved in, the ducts were full of caked-on dirt as if the system had never seen a filter...or should I say the coil was the filter??

In addition, this system was horribly installed from the get go and needs an entire replacement, ducts and all. I'll present my system in all it's glory someday, when I decide to do a complete change out.

Here's my current problem:

The system (air handler) keeps intermittently shutting off for some reason.

With the system set to the Auto position, the condenser runs just fine and doesn't shut off, even after the air handler shuts off and sometimes for long periods. Now I can't get the air handler to turn on at all.

It is set up with a primary that drains onto the ground near the condenser. There is no secondary drain, only a pan float switch. Awesome...I know.

My first instinct was to check to see if there was water in the pan shutting off the float switch. We've had a lot of problems keeping the primary drain cleared and I've had to shop-vac it out several times a year.

The pan is dry as a bone this time and I cannot get the air handler to turn on at all.

Could it be that the pan float switch is finally crapped out and stuck open/shut or is it something else?? I just don't know where to begin diagnosing this issue.

Any and all advise and recommendations would be most appreciated.

Thanks in advance.

Donnie


Last edited by DonnieC; 09-10-2011 at 01:06 AM.
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Old 09-10-2011, 03:18 AM   #2
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AC shutting on and off...


Set the thermostat to Fan on....blower motor should work. Check the float switch, move the magnetic up and down. The blower motor should turn on and off. After that, you can check if you get 24v from orange wire at the thermostat and also at reverse valve in condenser.

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Old 09-10-2011, 04:47 AM   #3
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AC shutting on and off...


On old Janitrols, and Goodmans. The fan is ran/controlled by a sequencer. they are known to fail.(on other brands also). So check the sequencer in the air handler.
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