My home AC blows warm air.

Anybody want to take a shot at helping me troubleshoot my Air Conditioner? It's not for my car but for my house.

It worked fine last summer. We even turned it on once over the winter when we had a house full of guests. It blew room temperature air then too. I'm not sure what any of the parts are called but I'll do my best.

There is a pipe that goes into my house. It's frozen (see pic). Inside the house, the ice melts and drips in the basement. There is a return line that goes back out to the AC unit. It is room temperature. The radiator things are room temperature as well.

There is a drain pipe that usually drips water but it hasn't been. I thought maybe it was plugged. I put a vacuum hose on it and sucked some water out.

What can I check for?
Here's the pic.

 

Wait until it gets hot outside. Otherwise the compressor won't work.
Ray

 

It's almost 70 degress. Isn't that hot enough?
-mark

 

Yes.. It looks like it needs to be recharged.. Frozen low pressure line means either to much freon or not enough.. :TU:

Either that or the air filter is plugged. But that usually causes the inside coil to freeze.

 

Yep. You're right on the money. Another common cause is the evaporator ("A" coil) plugged up with dust (from not changing filters often enough).
A plugged filter or coil will usually also cause poor airflow mostly noticeable in the rooms farthest from the furnace though.

 

Mine did the same thing two weeks ago and was low on freon . Low side pressure should have been about 50 but was only 12-13 . Put the gas in and now cooling great . Has been in low 80s last few days and nice and cool in house .

 

I have AC gauges. I'll check the low side.
I'll also check for dust.
-mark

 

you're looking for a low side pressure over 62 psi which is about 32 degrees. Below that and it will ice up. The actual low side pressure depends on the outdoor ambient temp and the air temp entering the evaporator.

 

How do you check a heat pump in the winter? Sorry to go off topic, but while the right people are here I thought I'd ask....

-Bill

 

you check them the same way, with gauges, the pressures are different in the winter. You connect your low side gauge to a low side port that connects to the suction line between the reversing valve and the compressor. If you connect your low side gauge to the port in the big line while it's in heating, you'll ruin your gauge in about a second.

 

Thanks - I thought so. My service guys won't do it until its 70+ outside. I guess I should find someone else!

- Bill

 

Hehehe.. Blam.:rant:

 

Do I understand you correctly , reverse the guage hook up ? What are the readings on a heat pump supposed to be ?
thanks , Mike

 

Bill, I have customers that want me to check their A/C early in the season and I ask them to wait until it gets over 70. You can check the refrigerant charge whenever you want but IMHO it's better to check the A/C when it's warm out and the heating when it's cool out. I'm not sure what your guy is telling you.

Mike, Sort of. The big line becomes the discharge line (high side) in heating. The newer heat pumps will have a third port that will be the low side in heating or cooling. On some of the older heat pumps, the high and low sides switched depending on mode. On the newer heat pumps, the ports on both refrigerant lines will be on the high side in heating, hense the third port. Also, the gauge ports or schrader valves on the outside of packaged heat pumps don't change from heating to cooling.

I also have to correct myself from an earlier post. Freezing, 32*F is 58 psi with R-22 not 62 like I said before.

At 70*F outside temp and 70*F inside temp I wouldn't expect to see lower than 60 psi low side pressure but pressures are only one thing I look at. Superheat is another major factor in determining if the charge is right. The other thing to look for in a central A/C system is a 18*F -+ 3*F differential across the evaporator coil. I take all these things into consideration. The pressures on a heat pump in cooling mode are identical to an A/C.

 

Andy ,
Thanks , I'm not crystal clear , which is normal , but I have a much better idea than before .
Mike

 

Mark... you have gotten the answers you need!

 

Yeah, this is pretty awesome!
-mark

 

Okay, this is the first time I have ever used these gauges. I bought them for the car, maybe they won't work for the home A/C?

The low pressure side has readings for R134a, R404a and R407a. There is also a bar and inHg psi reading.

When I checked the gauge, it was +36 on the R134a scale (if that helps).

 

the temperature pressure scales for those refrigerants are irrelevant to your a/c system. You have an R-22 system. Pressure is pressure though so what did the gauge read in psi? If it was 36 psi and the airflow is good and the coil is clear you need refrigerant. You should also install the high side gauge and see where that is to confirm a low charge.

 

The center scale on the gauge says inHg. It read 117psi on the low side and about hte same on the high side. It's 65* outside.