Help troubleshoot non-working heat pump

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Old 02-16-20, 08:09 AM
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Help troubleshoot non-working heat pump

Our 1996 roof mounted, 4 ton, Carrier heat pump in AZ is blowing air out at 60F. Outside temperature is 50F. AC picture

The fans come on but nothing else. I noticed this a couple of days ago. Our electricity consumption has not changed appreciably, which puzzles me. It sounds like the heat pump is not coming on.

I read that this could either be a fuse (easy) or refrigerant leak/compressor failure. If it is the latter, is this worth fixing given the age?

How would I go about troubleshooting this, I am pretty handy and have a multimeter. But no experience when it comes to AC stuff.

thank you for your time
 
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Old 02-16-20, 09:19 AM
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Many heat pumps have back up electric heat dependent on outside ambient temperatures in the operating area. If you're in a warm zone.... you may not have back up electric.

Your next step is to see if the condenser fan on the roof is running. If it's not then you need to check the power to the unit. Check it at the disconnect near the unit. If you have 240v at the disconnect it's possible that you are low on refrigerant.
 
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Old 02-16-20, 09:32 AM
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Is the condenser fan and compressor starting and running?
 
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Old 02-16-20, 09:53 AM
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Thanks guys, I appreciate the help.

To answer your questions. The condenser fan on the roof is running. The compressor does not appear to be coming on, I mean I cannot hear it kick on as usual. Should that not mean a drop in power usage?

I think this happened a couple of days ago, we have our brief perfect weather season in AZ so we didn't quite notice that the heat was not working. Also we do not have a backup electric/emergency heat feature. Its a packaged all in one heatpump system
 
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Old 02-16-20, 10:02 AM
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The auxiliary heat would be installed inside your package unit. It would not be mounted elsewhere.
If the compressor is not starting test the starting components/capacitor.
 
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Old 02-16-20, 10:38 AM
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Ok thanks, roughneck77, point noted about the aux heat. I just never saw a feature on our thermostat for it.

Ok found a video on how to identify and test starting components. Will go up on the roof this evening.

Though, I am wondering if I should just get a new AC given the age 26 years ( I read most last 10-12).
-If there is a refrigerant leak will the compressor still come on?
-Does the compressor have a fuse separate from the fans.
 
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Old 02-16-20, 10:50 AM
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Compressor shouldn’t have a separate fuse.
Since the condenser fan is coming on that rules out any sort of low pressure protection.
 
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Old 02-16-20, 12:37 PM
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As I mentioned.... you may not have aux heat. In warmer zones just a heat pump can supply enough heat. If the fan is running and the compressor is not points to either a compressor problem or a capacitor problem. It's easy and cost effective to replace the cap first.

A typical packaged heat pump would be protected with a +/- 30A breaker.
If you see large breakers like 50-60A...... then you do have aux heat.
 
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Old 02-17-20, 12:01 PM
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So thanks to your help, I was able to open and remove and test the capacitor. It has definitely failed. The wrinkle is the label has torn off partially so I cannot identify the specs. See picture capacitor label

Its a 4 ton heat pump, keying in the AC product number give me Capacitor dual run, 370vac 60/10uf oval from repairclinic. Does that sound about right? I know the voltage matching is not as important as getting the farads correct.

 
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Old 02-17-20, 12:31 PM
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I see the replacement cap Repair Clinic has listed. I'm not quite sure I'd agree but I haven't found a direct Carrier parts list yet for that unit.
 
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Old 02-17-20, 12:36 PM
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Ahhh I see I would think as long as the farads are high enough without blowing it up. But I am not knowledgeable with these things.

Also from what I can see of the existing capacitor label, it does not match the replacement from repairclinic. Carrier does not list a capacitor replacement for that unit.

What would you recommend? I cannot see the compressor label to see if anything can be gleaned from there.

edit: Ok what I have is a MARS 12254 60 MFD 440V, I was able to google search images and find the code for the label. Will replace and update if this is a success... thanks all for your help!! I saved a bunch of money here!
 

Last edited by MrSmithNV; 02-17-20 at 01:03 PM.
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Old 02-17-20, 01:31 PM
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That makes more sense. That will be a two wire capacitor used for the compressor only.
 
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