A/C Question

[WhiteOut]

I've had problems with my car not blowing cold air when the A/C is on this summer, its usually not a problem since I have the top down, but lately its been rainy and humid so I'd like to get it working right. So anyways I pressure tested my system earlier today and found that it was at around 22 psi, a bit low, so I put in about 3/4 a can of recharge to bring it up to 45 psi (ambient temp was about 80 degrees). Oddly enough the A/C still will not blow cold air. Whats going on? I can hear the compressor engage and disengage when I press the A/C button on the climate control so I know the compressor is at least pretending to work, and my system has a full charge of coolant, so why doesn't it blow cold air?

[god910]

Could be a plugged, umm... it's been like 3 years since I had an A/C class. The nozzle thingy... I'll post when I remember. :oops:

[GPdriver1986]

Could be a plugged, umm... it's been like 3 years since I had an A/C class. The nozzle thingy... I'll post when I remember.

 

Ya I know what you are talking about its a valve that goes from large diameter A/C hose to small diameter, its what makes the freon go cold, this can be demonstrated by poking a small hole in a can of A/C gas, the area around the hole turns cold. This valve is usually right beside the evaporator.

[GPdriver1986]

Oh I just thought of some stuff:

Is there water on the ground draining from the interior?

If you touch the pipes around the compressor are they cold?

 

If yes to all those questions its possible that your climate control heat/cold temp valve is stuck or not working properly. I know that on my 91 GP its electronic not vacum, if that helps.

[cutlassdude96]

did you take it for a spin after you did this :?:

[Whiskey River]

I've had problems with my car not blowing cold air when the A/C is on this summer, its usually not a problem since I have the top down, but lately its been rainy and humid so I'd like to get it working right. So anyways I pressure tested my system earlier today and found that it was at around 22 psi, a bit low, so I put in about 3/4 a can of recharge to bring it up to 45 psi (ambient temp was about 80 degrees). Oddly enough the A/C still will not blow cold air. Whats going on? I can hear the compressor engage and disengage when I press the A/C button on the climate control so I know the compressor is at least pretending to work, and my system has a full charge of coolant, so why doesn't it blow cold air?

 

If you had 45 psi, with the system off and at an 80 degree ambient, you are severly undercharged. It should read closer to 100 psi at 80 degrees.

[WhiteOut]

Seriously??? I should really have 100 psi on the low pressure side of the system??? I could swear that the pressure on the low side was only supposed to be between 40-50 psi. Can anyone confirm what the pressure should be at an ambient temp of 70-80 Farhenheit? That would certainly explain things.

 

I don't think its any sort of problem with a valve, there is a definite differance when I adjust the temperature control between 75 and 60, its just not blowing ice cold like it should when set to 60, its more like the vent is on.

 

And yes, I took the car for a 20 minute drive after charging, I even unhooked the battery and reset the ecm hoping that it would clear any low coolant codes that might stop the system from cooling properly. I know if the pressure got to low in my Trofeo the comp would shut the compressor off altogether. That doesn't seem to be the case here though since the compressor clutch can be heard engaging and disengaging.

 

So, again, can anyone confirm what the low side pressure should be at an ambient temp of around 75?

[Whiskey River]

Seriously??? I should really have 100 psi on the low pressure side of the system??? I could swear that the pressure on the low side was only supposed to be between 40-50 psi. Can anyone confirm what the pressure should be at an ambient temp of 70-80 Farhenheit? That would certainly explain things.

 

I don't think its any sort of problem with a valve, there is a definite differance when I adjust the temperature control between 75 and 60, its just not blowing ice cold like it should when set to 60, its more like the vent is on.

 

And yes, I took the car for a 20 minute drive after charging, I even unhooked the battery and reset the ecm hoping that it would clear any low coolant codes that might stop the system from cooling properly. I know if the pressure got to low in my Trofeo the comp would shut the compressor off altogether. That doesn't seem to be the case here though since the compressor clutch can be heard engaging and disengaging.

 

So, again, can anyone confirm what the low side pressure should be at an ambient temp of around 75?

 

The low side should be the same as the high side if the system hasn't been ran for an hour or so. Also, these cars are equipped with a V5 variable compressor, the clutch won't engage and disengage continually unless there is a pressure issue. Here is a link to the static pressures of refrigerant. It is actully closer to 86 psi static pressure. With the system on, your low side should be around 22 psi.

 

http://www.delanet.com/~pparish/pt-table.htm

[WhiteOut]

Interesting, so I should have charged the system closer to 80 psi, rather than the 45 psi or so I left it at. Thanks man, I'll let everyone know how it turns out.

[Whiskey River]

Interesting, so I should have charged the system closer to 80 psi, rather than the 45 psi or so I left it at. Thanks man, I'll let everyone know how it turns out.

 

Only charge it to 80 or so with the system off. Then you should be good to go. When the system is running, it should be around 22 psi.

[slick]

You should have someone press the button while you look at the compressor. On the outside of the compressor, when the engine is on, there will be a plate, maybe .25" in thickness, that isn't spinning. Once you press the button, it will start spinning.

 

Now, even though you hear the engine prepare itself for the A/C running, it may not be. When i didn't have the power wire hooked up to my compressor, and i pressed the button, the engine would still make the noise, and the rpm's would fluctuate for a second or two.

[WhiteOut]

Thanks for the replies. I'll check the clutch plate to make sure its actually engaging as well. I plan to do the complete fill later today after I get some sleep (I work 3rd shift).

[slick]

Hopefully you get her going!

[WhiteOut]

Well, I charged the system to 80 psi and it works wonderfully now. Thanks for your suggestions guys!!!