My York Stellar heat pump runs for some time normally. Then the thermostat light starts blinking 4 times (error code 4). However, the discharge line gets normally hot. It will work OK again for a time after I reset the error code.

Thanks for the help
PJ

I'm not sure what the 4 error code means if its defrost issue then it could possibly be a inermitting stuck reversing valve or relay by resetting the error code restes the relay, is the unit requiring defrosting or is it just the normal defrost cycle or just checking to see if it needs defrosting? If I'm not mistaken the reversing valve is normally in heat. Cycle unit to cool mode wait for the suction line to cool few moments then cycle unit off NOT POWER touch the suction line at the same time on the valve at the exit of the valve leaving the evap coil you want to feel if the line warms up if so the reversing valve is leaking or sticking between cycles and requires replacing if not. Then the relay could be hanging up on you or a weak defrost sensor bulb. Dip the bulb in ice water place a thermotor in the water and see what temperature the relay switches to defrost cycle see manual for temperature requirements good luck

Jimh92801,

Thanks for your quick response.
Sorry, I was a little hasty with my original note. Error code 4 is: "Discharge temperature did not reach appx. 90 degree F within 1 hour of compressor operation". However, this is actually not what happens. The temperature of the vapor line at the sensor (located within 3" of the compressor and before the reversal valve) is what it always was - very high. So is the temperature of the thick vapor line where it exits the Heat Pump.
I should mention, there is an error code 6 "Discharge sensor failure" It does not come on. Then again, there is only one light blinking at a time. No idea how the system would handle two simultaneous errors.

Here is some more to the story. The system was running fine prior to a Tech. coming out to check the Freon charge. He said the Freon level was a bit down but not much. Yet he put 2 pounds of Freon in. He did it in the cooling mode at an outside temperature of 40 to 45 degree F. After that, I noticed that the air temperature differential between intake duct and a vent was 38 degree F. That used to be about 20 degree F. Also the Freon lines and the indoor unit started vibrating producing a loud rumbling noise (in heat mode only). I called the service people again. They came out and found the discharge pressure in the heat mode at about 290 psi at an outside temperature of 40 degree F. Based on that, they removed some Freon which fixed the rumbling and vibrations and the air temperature differential is back to the normal 20 degree F.

However, now I have the error code 4 problem which shuts down the compressor every hour or so. To get it going again, I have to reset the error code. Just to mention it, during that hour or so, between error codes coming up, the system runs totally normal.

Sorry for the long write up but I thought I needed to provide a little more back ground.

I have one question, these temperature sensors, are that thermistors or thermo-couples? Any idea where I could get a replacement if the sensor should turn out to be bad. Also, is there perhaps a way to bypass this sensor temporarily just to prove whether it is the cause of the trouble or not?

Again, thanks so much for your help.

PJ

Based on the "rumbling" you describe, the sensor may have been damaged. Two pounds isn't "not much" to an average residential system. If this wasn't a problem before the system became overcharged, I would seek resolution from the service contractor.

Sorry for the delay in answering. In desperation, I actually removed the insulation from the discharge temperature sensor and found that the sensor was actually broken in two. Fortunately, the local distributor had the part in stock. I replaced it, re-set the yorkguard control unit and things are working OK again.
Thanks again for your help.