I need some help with this one- I've checked all the other threads, including the DIY adding the R134A DIY sticky, no luck. But i've seen CF come through so here goes:

The car:
-98 C5, 160k miles on the clock. I've been owner for the past 7.5 years and 120k miles.
-It has the Auto Dual zone unit.
-The A/C has never been serviced.
-It was working fine up til about a few weeks ago

The symptoms:
-A/C does not blow cold. It does not blow cold at all, but with the passenger side set to "coldest" the passenger side does feel a little cooler than the driver's.

Basic Diagnosis:
-No codes in the DIC (history or current)
-I visually checked and the compressor is spinning/starting when it's supposed to (along with the A/C button).

Advanced Diagnosis:
I busted out the HVAC pressure gauges reading the high and low- everything checks out fine. Static pressure reads correct, just over 100 PSI both about the same.

I then used the factory service manual, followed the chart for the performance test (run the engine and AC test)- that too appears fine, on a 80 degree day, 50% humidity, low was reading about 27 PSI and high was at 151 PSI, just about what the spec sheet calls for.

I followed the troubleshooting flowchart in the factory service manual step by step and everything appears to be working ok and within spec. It falls within (though right on the edge) of the "zone A" reading for those familiar with the manual. There might be humidity in the refrigerant lines but I don't see how this would have happened.

So before I break down and bend over and drive it into the repair shop, any ideas? Should I try to evacuate and then recharge the system? Something else I'm missing??

 

I know the 27 psi reading was what the spec sheet calls for. But I would buy a can fo coolant and bring the pressure up a little more. I would do the full can or stop at 35 psi if it gets that high.
I doubt you have any humidity in the lines.

By the way, I assume the radiator cooling fans came on when you turned the AC on. Correct?

 

I plan on doing this (the can) later today, hopefully it works...

Yes the radiator fans are coming on correctly (high and low- or parallel and series mode, respectively).

 

Sounds like your mixer baffle is fubared.

 

I'm having this exact problem. I'm afraid it's the AC actuator.

 

Not saying this is 100% true but in all cases I have found, if the actuator is bad, it will set a code in the computer.
He stated no codes so I doubt it would be the actuator out of position.

 

The actuator codes are set when the actuator gears are allowed to move out of range. I mean you could cut a gaping hole in the middle of the mixer door, your HVAC won't work for crap, and the actuators won't throw any codes because of it. I'm not saying this is what has happened just that I can envision a multitude of scenarios where the actuators think everything is fine but the door isn't operating as designed.

The OP has pretty much verified everything he can short of putting a hand on the evap core itself. And he has air movement, but it just isn't cold which would imply it's not moving past the evap core. Hence something is most likely awry with the mixer door.

Eric, will it blow hot?

 

Haven't tried the heat but I certainly can when I go home. Didn't want to turn the heat on it's pushing 100 degrees today Will the car even let you turn the heat on when it's that hot out (sorta like it won't let you turn on the AC if it's below 40 some degrees out)...

Other things I might have skipped mentioning - yes there is good air movement, it blows fine. It's definitely not the "vaccuum line behind the intake manifold that got disconnected" issue as I know what that's like

It does not matter if the car is driving or not driving, or how long it has been turned on etc.

I have not removed the dash to try to get to the Evap Core. So yes I'll try to check the mixer door if it's accessible by taking the blower motor out I presume?

 

Pretty sure it will as long as you crank it all the way up. If it starts blowing HOT when you do that, then at least you know the door is moving somewhat.

No, it's further down the chain than the blower. Good pics here...

http://forums.corvetteforum.com/c5-t...placement.html

 

Now that's a great thread, and somehow I miss it. Wonder if that's what the issue is... I'll poke around some more. At least it does not seem like it's my compressor unfortunately the car had to pick the hottest day out of the year to lose the AC! Sheesh

On another note, my low side shrader valve is leaking. Looks like it's a fairly easy repair with the right tool though or it might be easier just to take it somewhere...

 

I cleared them waited and they just come right back. I heard what sounded like movement but who could tell. I had my High & Low checked and everything was in tolerance.

 

So I just changed my actuator driver side. The codes are clear but the air is still HOT on the driver side. I heard the actuator set it self. I have the battery unhooked right now. Any suggestions????

 

Did some more pecking around- yup turning the control to heat, it blew hot alright so then I took some more readings and noticed the high side seemed a bit low but the low side was OK. I spent the $10 to buy a 12 oz can of R134A, used the tool to pierce the side of the can and slowly added the refrigerant to the low side. As I was doing it the low side remained steady and the high side got higher. Then the AC started blowing cold again the passenger side does feel like it's a little bit cooler than the drivers side, but it's much better than what it was so I'll just live with that (yes I pulled the fuse to have it recalibrate itself) instead of tearin apart the dash to fiddle with the actuators .

I have a feeling the damn leaky schrader valve is the cause of the refrigerant going low. I'll just have to get the tool to try to change it out. Surprise it's lasted this long, considering it sits right next to the exhaust manifold, gets a ton of heat cycling! Hopefully this was all it was.. I must not have read the chart right the first time or my humidity gauge was off (one of those wireless weatherstation things).

 

Cool, glad you got it figured out. I guess I never looked at the placement of those valves.

Reindexing the driver side actuator is pretty easy. It took me about 1.5 hours, and I'd never done it before.