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Ask Daniel Plourde Your Own Question
Daniel Plourde
Daniel Plourde, HVAC Technician
Category: HVAC
Satisfied Customers: 327
Experience:  hvac technichian at performance plumbing and heating
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I have a trane Split System heat pump. Installed in 2002.

Customer Question

I have a trane Split System heat pump. Installed in 2002. Put in new ouside unit in 2013. 2TWB3060A1000. Outside near compressor lines were icing up. Called technician who said it had a small Freon leak. He put in 3lbs and added stop leak. Now when it starts up fan and compressor are running fine. After about 10 minutes the the compressor starts making a hissing noise for 5 minutes then shuts down. Fan is still running and no cool air inside. Technician thinks I should replace everything cannot tell me whats wrong. If it is not to hot outside the unit runs fine.
JA: Did you double-check the thermostat's settings? And what about the filters?
Customer: Filter are clean and Thermostat is fine. I have to let unit be turned for awhile and then restart to get it to cool.
JA: Do you plan on doing the work yourself?
Customer: If I can but if it involves Freon I will use someone else.
JA: Anything else we should know to help you best?
Customer: I think outside unit may be covered under warranty. Capacitor looks OK but I can buy those for $13 so I may replace those myself. Unit looks new.
Submitted: 2 months ago.
Category: HVAC
Expert:  Daniel Plourde replied 2 months ago.

hi i am dan i can help you with this. unfortunately it is not an easy fix for your system to work. the worst thing is having the stop leak in your system. the compressor making the hissing noise means the pressure is getting so high that it is bypassing the valves in the compressor and then it overheats and shuts off. that means that either the valves in the compressor or the expansion valve at the indoor coil is gummed up most likely by the stop leak. i personally never use stop leak as i see it cause so many problems like yours, also on newer units punting stop leak in the system will void any warranties from the manufacturer. the way to fix leaks is to spend the time and search for the leak and fix it. in order to determine if it is a problem in the compressor or the expansion valve i would need to know the pressures and temperatures of the system running. if this helps you or if you have any more questions about this please let me know.

Customer: replied 2 months ago.
The AC unit never had stop since it was replaced in 2013. yesterday we had a thunderstorm that brought outside temperatures from 95 to 80. After it cooled down outside my AC worked fine and we had inside temp to 72. Why does it do this when it just gets really hot ? I will get tech to check pressures and temp. Will not be last guy that put stop leak in system.
Expert:  Daniel Plourde replied 2 months ago.

the problem you are having is the system is building up too much pressure. the pressure is directly related to the temperatures. as the temperature outside rises so does the high side pressure in the system then causing the compressor to overheat. another possibility is that the system may have been overcharged with refrigerant. the system will need to be checked and calculate the superheat and subcooling temperatures in order to see what the system is doing.