Started blowing warm the other day (105 outside). Stopped and put in a can of 134 with the built in gauge from WalMart. Low side pressure said 15 on the can, so it held the hold can (18oz) and got up to 45psi (range based on ambient air temp said 45-55psi) and wouldn't go any higher. Ran cool again for the rest of the day, then the next day it was back to warm again.

I'm assuming just a leak, and nothing more major. Just need to know where to look and if the colored dyes do any good at helping locate.

BTW. the blend door is awol.

 

I think low side is suppose to be 70 and get a can of super seal

 

Uh more like 45. 70 will be extremely over charged. The low side psi is about the same as the evaporate core surface temp. Below 32 (low charge) causes it to ice the condensation. I try to set mine at 40. Also, the free with a can gauge is about as accurate as putting you thumb over the hole and feeling what psi it has in it. You must have a decent set of gauges and the knowledge to know what they say to you. Just a quick can can do some real damage if you don't know what's going on inside, although on these trucks, low freon is the most common issue, aka leak in the evaporate core.

 

There's lots of good info here and online. Before you go too much further, do some research. Ac systems are very simple and very owner serviceable with the correct tools and knowledge.

 

AND do not use R134a with the sealer crap in it - many refer to these as "DEATH CANS". This stuff is akin to the radiator stop leak stuff - it may stop your leak but will probably stop up the rest of the system as well.

 

Depends on Ambient Temperature. At 80 degrees F Ambient Suction Pressure should be 45 psi +/- 5 and Discharge approx 190 psi, at 90 degrees F Ambient Suction pressure should be 88 psi +/- 5 and Discharge 240 psi, At 100 degrees Ambient Suction pressure should be 65 +/- 5 and Discharge almost 300 psi. Don't worry too much about discharge press readings. Suction pressures may be a better indication of proper charge. Of course, as long as you are getting cold air out the center vent suction pressure may not match these values (i.e. braille method of charging)