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airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8269
Experience:  Furnace, A/C and heat pump specialist.
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I have a Rheem split heat pump system (Model 13PJL42A01). It

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I have a Rheem split heat pump system (Model 13PJL42A01). It worked well last Winter and this past Summer. I have just turned on the heat and while in the heat mode the condenser motor and compressor come on. It will only run for about a minute then both shut off.. The logic board shows that it has gone in to Low Pressure lock out and the inside unit goes into auxillary heat mode to heat the house. Can you suggest what I can do to correct the problem so that the heat pump will run? I checked the unit in the cooling cycle and the 410A pressures look good but when put back into the heat mode it shuts down again.

Hello. My name is XXXXX XXXXX I'll do my best to help. Troubleshooting often requires meters and test equipment. Let's get started and see what we can do.
If you have verified that the refrigerant charge is good, you most likely have a sticking txv (thermal expansion valve) in the outdoor unit. Very common problem.
If valve sticks closed,refrigerant can not get back through outdoor coil so suction pressure will go all the way to zero.
Customer: replied 3 years ago.

The outdoor unit has a txv? Where would it be located? how can I unstick it? will this require me to draw the system down, replace and recharge the sytem?

Yes the indoor txv meters in cool mode, the outdoor txv meters in heat mode.It will be located in the liquid line just before it enters the outdoor coil (between small service valve and feeder tubes).
You can try tapping on it with a wrench to see if it will unstick.
Ultimately will probably have to replace.Will require some welding and yes, you will have to recover refrigerant, replace txv and the evacuate the system before recharging.
Customer: replied 3 years ago.

I am in the office now... I will try later when I get home.. If tapping with the wrench doesn't work, do you have any other ideas of what it might be and i might can try before I evacuate the system and replace the txv?

If it is cutting off on low pressure and freon is good, it has to be either a restriction in the refrigerant circuit or low airflow across outdoor coil.Coil could be dirty or outdoor fan not running, but those would be obvious.
Using a pipe clamp thermometer, check refigerant line temps on each side of reversing valve, t xv, or filter driers. A drastic temp diff will indicate restriction.
Customer: replied 3 years ago.

I appreciate your answers to my questions and the suggestions to solve the problem... Doesn't get too cold in SC but still need that heat pump working! You have me some great suggestions.. Thanks!

THanks for allowing me to work with you. Headed out door to dr office, but will check back when I return. If satisfied with answer please rate accordingly.I will address any other questions as soon as I return.Thanks again
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