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Old 07-29-2009, 09:17 AM   #1
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Could a failed condensor fan raise pressure/trip high pressure limit switch? (Rheem)


My HP system was doing great last night at bedtime. (100 degrees outdoor ambient, 75 indoors).

However a couple hours later the house started getting warm and I observed that the condensor was dead w/air handler still running. (no outdoor fan or compressor running). I cycled power and the AH came on again but the condensor didn't even after the 5 minute delay. (I'm 100% sure the fan didn't come on and don't think the compressor did but I could be mistaken.)

This morning I tried it again and the outdoor fan was dead but the compressor came on.

This afternoon I'm going to diagnose it further however my theory is that the outdoor fan motor's starting capacitor went out. Without the fan running would pressure build up since condensing activity was severly limited by lack of airflow by a dead fan? I suspect the higher then normal pressure tripped the high pressure limit lockout. Maybe by this morning pressure had equalized enough for the compressor to start but the outdoor fan remained dead.

The other theory I had was that there was a unexplained loss of refrigerant that tripped the low pressure shutdown. However if that was the case why did the compressor start up fine this morning when it was 30 degrees cooler outdoors and thus even lower pressure then last night? There was absolutely no sign of diminished cooling up until the time it failed.

I'll check the Ranco debug codes tonight and test the starting capacitor. Fortunatly I have a spare.

I'm just curious if my theory makes any sense?

This is a 4T Rheem RPNE system.

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Old 07-29-2009, 11:20 AM   #2
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Could a failed condensor fan raise pressure/trip high pressure limit switch? (Rheem)


when was last time you took the skins off to clean the condenser?

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Old 07-29-2009, 11:28 AM   #3
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Could a failed condensor fan raise pressure/trip high pressure limit switch? (Rheem)


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when was last time you took the skins off to clean the condenser?
A couple months ago. The condensor is clean enough to eat off of.

The system is only a few years old.
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Old 07-29-2009, 11:43 AM   #4
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Could a failed condensor fan raise pressure/trip high pressure limit switch? (Rheem)


Condenser motor should be under warranty. Contact the factory in your AC paper work for the factory number. They should be able to advise you with most speed who can replace it locally.
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Old 07-29-2009, 05:04 PM   #5
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Could a failed condensor fan raise pressure/trip high pressure limit switch? (Rheem)


Here's the culprit. It was a 60/10 440 run capacitor that was completely open.

Today's likely to be the hottest day on record here in Portland and this stupid capacitor decides to commit suicide.

There's not a single capacitor of this value in all of Portland. The nearest one is at a Grainger branch in Chicago!!

Luckily Johnstone had some Mars Turbo 200's in stock and I jumpered one to 57.5/10 and it works like a champ.

The old was only about 2.5 years old and made by Aerovox. I guess that's one brand to avoid!!!
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Old 07-30-2009, 01:05 PM   #6
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Could a failed condensor fan raise pressure/trip high pressure limit switch? (Rheem)


You sure about that rating?

I have my suspicions you may be wrong.
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Old 07-30-2009, 02:04 PM   #7
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Could a failed condensor fan raise pressure/trip high pressure limit switch? (Rheem)


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You sure about that rating?

I have my suspicions you may be wrong.
Yep, Rheem calls out a P/N 43-26271-45 (60/10 440) in their current RPNE parts list document. Maybe they upped the voltage rating from several years ago - don't know.

Even if it was a 370, I prefer a 440.

System's working like a champ now that this crappy plastic Aerovox capacitor was replaced!!

Thanks for the replies!


Last edited by hennyh; 07-30-2009 at 02:07 PM.
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