A/C Turns Warm At Times?

[Duplex Dave]

Got My '97 last Nov. The A/C always blows nice and cold, strong. Recently in the 100 deg. weather 2 weeks ago the A/C just started blowing warm. I switched the intake to fresh air and it slowly went back to normal. I figured it was the extreme heat.
Yesterday it started doing the same thing only it was about 80-85 degrees. So, could a line be freezing up? Should I run it on fresh air all the time? Anyone else have this happen?
It normally blows very cold compared to my T-100 so I think the refridgerant should be good.

 

[neal0124]

That sounds like an expansion valve problem. Mine did the same thing until I removed the entire AC unit from the truck, cleaned everything, replaced the expansion valve and re-charged the system. Now it blows so cold it will freeze your face. There is a thread in the 80's FAQ section.

 

[fj80toyman]

Could it be related to the coolant temp? In other words, do you think it got hot enough to get the coolant up past 108deg C? If so, that's the point where the A/C automatically shuts off until the coolant drops below 103deg C when it turns back on. My experience is that the ambient temp usually has to be around 100deg F and under a load (going up a hill) to get it that hot, but you might have other cooling issues that push your coolant up quickly.

Dan.

 

[dude47]

Start with the simple things first, go to harbor freight(Find yourself a 20% off coupon first) buy a set of AC gauges. Check and see what the pressure of your system is while running with the AC on high. Odds are with a 17 year old vehicle freon might just be a little low. I am pretty sure that a 97' will take R12 freon. While charging the system hold RPMS up around 2k. If you are having a hard time getting the full charge in you can set the can in a pot of warm water to help the freon evaporate and push into the AC system. The can should be held upright while filling the AC system otherwise liquid freon can be introduced into the low pressure side of the AC system and damage the Compressor. If the system gets to the point where it is too low you might have to find the low pressure switch that keeps the compressor clutch from engaging when the pressure is low enough to cause damage to the compressor and jump the wires together to get it to activate the clutch.