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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 8685
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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Help. My house is getting warm. I just turned off my heat

Resolved Question:

Help. My house is getting warm. I just turned off my heat pump/ac system to change out the intake filter. I then turned it back on. I noticed the house was not cooling well. I then noticed the outside unit fan is spinning but no compressor working. I was wondering if the system is low on Freon. I hooked up gauges. With the system not running, it shows around85 psi. The outside temp is now 91 degrees. Is this enough pressure for the system to run? I also figured if it was low on Freon, the fan wouldn't come on either. It looks like the fan and the compressor works off the same contactor. What would be the best way to check if it is the run capacitor or the compressor?
Submitted: 4 years ago.
Category: HVAC
Expert:  Phil replied 4 years ago.
Welcome to Just Answer !

Getting an accurate read on the pressures in a system needs to be done with the compressor running. With the compressor OFF the read does you no good, However, depending on what refrigerant the system uses, 85 psig with the compressor off is very low.

Tell me please which filter you are referring to. Is it an air filter in the air handler? and tell me which refrigerant is listed on the outside unit name plate.

We can go from there

Customer: replied 4 years ago.
Sorry I took so long to get back to you. It is R-22 freon. The filter is at the return vent. I did replace the run capacitor. No change. I then confirmed compressor power after the contactor, and then right at the compressor while checking wires. I ran cool water over the compressor wondering if it overheated and is thermal protected. I unplugged the condensor fan so I can hear the compressor. It did not sound good at all. Like marbles banging around. I then Replaced the outside unit with a good working used one. Only thing is it is a 13 seer opposed to the original 10 seer. Everything worked out well and is cooling excellent. I was wondering if I have to or should change the orfice. The only concern I have now is that the compressor is running a little noisy. I'm wondering if there is a restriction somewhere in the system. This is where I'm at now.
Expert:  Phil replied 4 years ago.
Hello again, thanks for the information.

While you and I are discussing thus hold off on any changes until after you and I discuss the situation..that way we can go step by step and avoid any complications.

Going to a 13 SEER of the same btu rating will not require you to change the metering orifice on the inside unit... the higher SEER rated units simply run lower head pressures in hot weather is all... and the SEER 10 metering orifice will *generally accommodate that. but we have to check a few things.

I need to know the suction pressure taken at the condensing unit when the unit has been running for a while and it is between 72 and 74 deg F in the house...I need that pressure reading.

And at the same time I need the head pressure reading, and the outside air temperature at that time.

And...I need to know if the suction line is cool, cold, sweating or icing at the compressor or not.... and if the compressor body has any condensate or ice on it where the suction line attach's, and if the bottom of the crankcase is cool.

That will tell me if the metering device is too large or not, and if the system is flooding liquid back to the compressor or not.... if liquid refrigerant is flooded back to the compressor it will make a rattling noise and damage the compressor over a fairly short period of time... a day or two.

Get me that data, we can go from there.

Customer: replied 4 years ago.
Hello. Right now the house temp is at 75 degrees. The outside temp is 84. The low side is now reading 45. And the high side is at 115. The suction line is cold and sweating up to the compressor. At the top of the compressor, the top corner where the suction is is sweating. Nothing icing up. The bottom of the compressor is at 92 degrees. That is with a temp gun at an angle so I don't know how affective that reading is. I can get more readings once the house inside temp lowers. It doesn't sound as noisy as it did yesterday when the house was pretty warm and muggy. But still has a buzzing sound.
Expert:  Phil replied 4 years ago.
Hello again, your head pressure should be way above 115 psig when it is 84F outside... it should be between 210 and 215 psig.

The suction pressure should be between 60 and 62 psig with the house at 74 F inside.

At 45 psig suction, the suction line would absolutely not be would be iced. OR... the suction line would be warm due to not enough refrigerant in the system. There is an error in taking the suction pressure reading for sure.


The very first thing we need to do is examine the way you are taking those pressure readings in order to be sure the suction pressure is not actually in the 60 psig range, and the head pressure is not actually in the 210 psig range... make sure your gages read 0 when disconnected... and do whatever else you can to insure the gages are working well and that you have them connected properly.

The next thing we need to do is take an amperage reading on the wires that run to the compressor... the wire coming directly off of the contactor and going to the compressor should read near the maximum amperage rating of the compressor when it is over 100F outside and with the house above 78F inside... that full load amperage (FLA) is stamped on the name plate of the outside unit. I need that number.

You need a clamp around type amp meter to take the amperage reading.

Let me know, we can go from there.

Customer: replied 4 years ago.
Sorry I didn't get back to ya sooner. I had to leave on a work trip. I would like to pay you for all your help and info. I had my system serviced since I had to leave, and didn't want to leave family members boiling in the house. I had the line set replaced. It had a couple of good kinks in it. Thanks! You were very very informative
Expert:  Phil replied 4 years ago.
Hello again! I hope your trip was successful and am glad you got a good service man in who was able to spot the kinked line problem.

I will put up the rating screen now so you can rate my service.

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