Vehicle A/C Help

[meyer4589]

I bought my parents 2001 suburban that has been in storage. The vehicle is 99% rust free and everything works besides the A/C. So far I have confirmed that the system is full and the clutch does kick on when you turn the system on. I get warm/hot air out of the vents and can hear a hissing noise through inside the cab. Is there a common issue I should be looking for? Pressure switch, bad service ports leaking? Trying to diy this before I take it to a shop.

 

[d.kaufman]

I bought my parents 2001 suburban that has been in storage. The vehicle is 99% rust free and everything works besides the A/C. So far I have confirmed that the system is full and the clutch does kick on when you turn the system on. I get warm/hot air out of the vents and can hear a hissing noise through inside the cab. Is there a common issue I should be looking for? Pressure switch, bad service ports leaking? Trying to diy this before I take it to a shop.

If AC has good charge and the compressor is cycling, I'd say something with the blend door. I know back on some early model vehicles (pre 2000s) the blend door is controlled by vacuum. Not sure if that's the case on your specific vehicle, but could explain the hissing sound if it is

 

[Rookie]

On my 02 suburban, it was the control knobs. Didn't matter where you set it, you were getting hot air.

 

[indyblue]

How did you verify system is full?
If it has refrigerant then either bad compressor, clogged orifice, clogged receiver/ dryer.

Are the lines to/from the evaporator cold?

 

[meyer4589]

How did you verify system is full?
If it has refrigerant then either bad compressor, clogged orifice, clogged receiver/ dryer.

Are the lines to/from the evaporator cold?

I just put a basic gauge with a Freon can on it. I’m not sure which line is which but one seemed hot and the other cold

 

[Ark]

I bought my parents 2001 suburban that has been in storage. The vehicle is 99% rust free and everything works besides the A/C. So far I have confirmed that the system is full and the clutch does kick on when you turn the system on. I get warm/hot air out of the vents and can hear a hissing noise through inside the cab. Is there a common issue I should be looking for? Pressure switch, bad service ports leaking? Trying to diy this before I take it to a shop.

Hissing noise may indicate a vacuum leak. A couple minutes of googling makes it look like 2001 is too new to still have vacuum operated blend doors, though.

If the system is charged and the compressor runs normally, then it is circulating refrigerant and should be cooling. If you are observing normal operation of the compressor and normal pressure ranges on the gauges, then chances are the evaporator core is cold and it's just not getting air blown over it. Youtube makes it look like the dash is easy to take apart and the blend actuators easy to get to. So you could take the dash apart enough to observe them while you manipulate the controls, or even operate an actuator manually. Might be able to access the evaporator core directly and feel if it gets cold. Also if you are getting definite cold feeling and condensation on one of the A/C lines, the system is working.

Can you change vents? Will it switch from defrost to dash to lower vents?

The noise may be nothing, unless you can track it down by ear. My first guess is the blend actuator has failed to the warm side. They do wear out. Your noise might even be the failed actuator trying to run.

 

[Jaybird1980]

The hissing could be the expansion valve. Is there any frost on it or the evaporator. Low pressure can make it hiss more also.

The blend door stuck can also cause a wind whistling sound and also cause the no cold air issue.

The control unit could cause it.

I would look at blend door actuator to see if they move when the controls are changed, and go from there.

 

[Gunmetalgray]

If the compressor clutch is clicking on and off every few seconds, the system is low on refrigerant and the clutch is disengaging to protect the compressor. If it stays on, should be good to move on to other causes. The 05's definitely have blend door actuator issues for sure, probably the same for other year models as well, the gear teeth strip and the door won't be set in the proper position with respect to the control setting. Replacing some blend door actuators is a pain just from an access standpoint but it can be done.
https://www.1aauto.com/how-to-replace-door-actuator-2000-06-chevy-suburban/video/47423

 

[meyer4589]

Well I dove more into it tonight. Took the actuator off and manually moved the arm and still have no cold air out of the vents. Compressor kicking on/off every 20 seconds or so. Am I low on Freon and have a leak somewhere?

 

[GLOCKMAN23C]

Well I dove more into it tonight. Took the actuator off and manually moved the arm and still have no cold air out of the vents. Compressor kicking on/off every 20 seconds or so. Am I low on Freon and have a leak somewhere?

Fast cycling is an indication of a low charge. Look for wet or damp spots around connections and the condenser, if nothing is obvious, it could be the evaperator.

 

[ChristianPatriot]

Well I dove more into it tonight. Took the actuator off and manually moved the arm and still have no cold air out of the vents. Compressor kicking on/off every 20 seconds or so. Am I low on Freon and have a leak somewhere?

Auto a/c systems are (usually) factory charged with a dye that glows under a black light. Might make it easier to spot a leak.

 

[Ark]

Well I dove more into it tonight. Took the actuator off and manually moved the arm and still have no cold air out of the vents. Compressor kicking on/off every 20 seconds or so. Am I low on Freon and have a leak somewhere?

20 seconds sounds kinda fast. You or somebody needs to hook up actual AC gauges and compare the pressures to the spec.

 

[cburnworth]

on another note with a different vehicle. I have a 2003 envoy and the rear lines were rusted out. I had to disconnect them and install a block on them.

 

[meyer4589]

Got the AC going and it cools running down the road, but at idle and in traffic blows warm. I’m thinking maybe fan clutch

 

[WebSnyper]

Got the AC going and it cools running down the road, but at idle and in traffic blows warm. I’m thinking maybe fan clutch

How did you get it going?

 

[meyer4589]

How did you get it going?

New pressure switch

 

[BiscuitsandGravy]

New pressure switch

Q&d trick is to short out the connector w a jumper or paper clip.

 

[ChristianPatriot]

Got the AC going and it cools running down the road, but at idle and in traffic blows warm. I’m thinking maybe fan clutch

Yep. Condenser’s need airflow. It could be dirty. Have you checked the front end to see if it clogged with dirt or anything?

 

[ghitch75]

Got the AC going and it cools running down the road, but at idle and in traffic blows warm. I’m thinking maybe fan clutch

a little low on freon will make it act like you said....it the compressor cycling at idle?

 

[Ark]

New pressure switch

Low charge will also cause lackluster cooling at low RPM.