98 5.0l cold AC only with MAX AC at idle

[BruceExploder]

Just took my car in for an ac recharge after not having AC the two years I’ve owned it. I turned it to max ac and felt cold air for the first time in my XLT ever!

turned it off and drove home. Later on I went around the block and noticed it was only cold At idle any raise in Roma and it blew warm. I messed with the switches and turned it to AC instead of max and it had pure HOT air coming off the vents. What should I check before I give up and take it to the mechanic?

also he broke the heater control valve in accident while recharging the air and replaced it with a new one could that have anything to do with it?

 

[umopepisdn]

Just took my car in for an ac recharge after not having AC the two years I’ve owned it. I turned it to max ac and felt cold air for the first time in my XLT ever!

turned it off and drove home. Later on I went around the block and noticed it was only cold At idle any raise in Roma and it blew warm. I messed with the switches and turned it to AC instead of max and it had pure HOT air coming off the vents. What should I check before I give up and take it to the mechanic?

also he broke the heater control valve in accident while recharging the air and replaced it with a new one could that have anything to do with it?

A set of AC gauges can tell you a lot. I’d start with checking the high and low side pressures.

 

[1998Exp]

Just took my car in for an ac recharge after not having AC the two years I’ve owned it. I turned it to max ac and felt cold air for the first time in my XLT ever!

turned it off and drove home. Later on I went around the block and noticed it was only cold At idle any raise in Roma and it blew warm. I messed with the switches and turned it to AC instead of max and it had pure HOT air coming off the vents. What should I check before I give up and take it to the mechanic?

also he broke the heater control valve in accident while recharging the air and replaced it with a new one could that have anything to do with it?

Had to wonder for a while what Roma is - my best guess is that you posted this from a smartphone and it -- not so smartly -- decided to turn RPM into Roma...

Edit: If the mechanic forgot to attach the vacuum control line to the new valve (or it disconnected later), it could be the problem -- see below.

Highly unlikely that replacing the heater valve has much to do with your problem. And, incidentally, replacing it was probably a good thing. A few months ago my 20+ years old valve decided to split open miles away from civilization and left me stranded.

As someone mentioned already, measuring high and low side pressure can tell a lot, but before that, I'd suggest to simply take a look and observe the compressor clutch as you increase the RPM. It may be disengaging instantly as you just open the throttle a bit. The other possibility is that you have a hole or a loose connection in the vacuum source for the HVAC controls. Increasing the RPM drops the vacuum, and the problem manifests itself when the system goes to the default position - defrost.