New to the forum, mostly because I'm stumped and have nowhere else to go but a mechanic...

I had two problems, and I believe one is fixed and the other has me scratching. Background: driving my 'burb, the A/C wasn't keeping up with the St Louis heat and humidity...well, mostly the heat. Refrigerant pressure was on the low end of good, and after a shot of 134 with some sealant, the rear blows ice cold. However, the front (dual-zone) does not.

I had suspected the door actuator because there have been a couple times when it had a kind of its own, and maxed the heat regardless of its setting, even though it was only once or twice. But that doesn't explain the passenger zone. While the rear blows ice cold, the front zones are mediocre at best, and inadequate at 90+ degrees (not to mention humidity over 70% at times). I pulled the dash to check the driver's side actuator, and it wants to turn continually, so I am going to replace it (I count it fixed because it appears to be an easy install). But even when I manually turn the A/C door by hand to each extreme, the heat works perfectly, but the cold is still pathetic.

So I'm stumped, an I'm hoping someone else can give me some advice.

Zac

 

probably low on refrigerant but now that theres sealant in the system you'll have a hard time finding a shop that will work on it.

 

It's not low, unless there is a second compressor and set of refrigerant lines. I checked it, and it's at the high end of the PSI range. Also, the back blows ice cold.

Zac

 

pressures can be effected by many things just because the pressure is high doesn't mean its full or a good clean charge. If you manually put the door full cold and its still not cold checking the refrigerant charge is the first thing to do.

 

But that doesn't answer the question about only finding one set of lines and one compressor. If the rear blows ice cold, then I dint see how it could be the lines.

Zac

 

Could be a clogged line to the front evaporator.

 

How can this be checked by a home mechanic?

 

the front and rear work off of the same compressor and same refrigerant charge, if the system isn't at capacity then one end may not work as well. Step 1 for diagnosing any AC complaint like this is checking the refrigerant charge. Even if you "topped it off" with a can theres a good chance of air in the system which will cause issues similar to your complaint.