LS1 Racing

iTrader: (15)

Noticed this issue on '02 Camaro last summer, and now that it's summer again, it happened yesterday.

Basically, when you turn the A/C on, it blows nice a lot of nice, cold air. After driving for 50 or 60 miles on the highway, the VOLUME of air coming out of the vents drops to almost nothing, but the air that does come out is still very cold. I have to turn off the A/C or switch it over just to "fan" for about 30 minutes or so, after which it will blow like normal. I don't think it's the fan because as soon as I switch from A/C to fan -only, it blows the usual amount of air.

Any ideas on this? I'm guessing that something might be iceing up, but I'm not sure.

Any help would be greatly appreciated.

wssix99

iTrader: (5)

Slow vacuum leak causing the vent positions to switch?

otiger50

one simple thing you could try is to try to change the cabin air filter. If that doesn't work then try changing out fuses and switches.
I was helping out a friend with his Saab that would blow almost no air, they had changed out the blower motor. The filter needed changed badly, but that didn't fix it. I ran all over town getting new switches, and all of the fuses looked fine. Then, I was stumped. I was standing there looking at the fuse panel and there was a 50 amp fuse (I don't remember what exactly but was for but it was cabin air related) that looked fine but I switched it out anyways. Fixed the problem! Idk y but o well!

LS1 Racing

iTrader: (15)

That hadn't occurred to me, however, the air isn't coming out of the defroster or footwells, either.

These cars don't have cabin air filters. Thanks for taking the time to respond, though!

SilverSS07

iTrader: (1)

Do you have access to a gauge set? I would check the pressures just to see where they're at. Also does the drain seem to be draining good? Might check to see if it's clogged. Does it happen after driving continuously without stopping 50 or 60 miles? My Dodge truck did that and it was because where the drain pan came out of the firewall there was no 90* fitting on it-just came straight out. The continuous air blowing on it wouldn't let it drain. It would drain when you would slow down and hit the brakes. I put a 90* hose on it and all is good.

wssix99

iTrader: (5)

Maybe the leak is not at the master hose in the engine bay (like most similar issues) and is isolated at the console switch or at the actuator. I am not near my manuals with the diagrams, but wonder if its possible for a leak local to the actuators to cut off all the vents at one time?

Dal1as

I had the same issue. After a bunch of research their is a canister that is located under our battery that deteriorates over time and loses pressure. It is part of our vacuum system. I need to fix mine also.

01WS6/tamu

iTrader: (37)

The compressor is a variable displacement compressor and the valving internally is going bad not allowing the compressor to regulate correctly and the evaporator is freezing up. Cheapest fix is to turn the ac off once it happens for a few miles to let the evap defrost or bend over and put a compressor on it.

Had this happen several times through the years on gm variable displacement compressors. It's not a vacuum problem that only effects mode door positioning.

LS1 Racing

iTrader: (15)

This is exactly what I do. After a few minutes, I switch back to A/C and it blows cold again.

wssix99

iTrader: (5)

This could definitely happen easily, particularly if the OP is still located in Norway but the original post said that the "volume" of air was dropping.

If the compressor was freezing, the volume of air should stay constant - the temperature would just raise.

If the volume is dropping, the fan or diverter doors must be the culprit, right?

Marc 85Z28

iTrader: (8)

Evaporator is freezing up. If you're going to cruise on the highway for extended periods with the AC on, turn the blower to a higher speed and/or run it in the vent position, not recirculate. This will prevent the freezing condition.

01WS6/tamu

iTrader: (37)

The evaporator freezes up causing a drop in air volume and the suction line all the way back to the compressor will turn into a snow ball because it is flooding the compressor.

wssix99

iTrader: (5)

Please disregard my last post. For some reason, I was thinking orifice tube when I read evaporator.



This has happened to me personally on a residential A/C coil.

I'd think that this freezing would introduce water inside the cabin and create a bit of a mess and/or mold problem in the duct work, right?

Marc 85Z28

iTrader: (8)

Water in the cabin could only happen if the evaporator drain was clogged and the HVAC filled up to a seam where a leak could occur. Same deal with mold growth... only if the drain clogs. Anytime there is moisture in the air the evaporator will be wet with the compressor running. Removing moisture from the air is half of it's job.

I PREFER that my vehicles run on the edge of freezing the evaporator which is why I run everything I own slightly undercharged with an orifice of my spec (when possible). I like a 34F vent temp on a humid 90F day!

AmDWs6

the evaporator is freezing causing the blower to have a hard time pulling air, it happened on a friends golf.

Air passes through the evaporator if it freezes it basically closes or restricts air.

01WS6/tamu

iTrader: (37)

Geez I'd love to have a high of 90 for the day it's that warm by 9-10 in the morning during the summer here. Lucky SOB's

Marc 85Z28

iTrader: (8)

We see humid triple digit temps here too, but I don't get 34F vent temps with that kind of ambient air

LS1 Racing

iTrader: (15)

Thank you all for explaining this.

Sounds like I'll need a compressor at some point. Meanwhile, I guess I'll live with it.

01WS6/tamu

iTrader: (37)

It will last for years to come just by turning it off once the air volume starts to drop. My vote if it cools well leave it alone unless you have bank to put new gm parts in it. Parts house and rebuilt parts are junk.

RockinWs6

Check the charge before you change anything, It maybe on the low side. Try adding 2-3 ozs and see if the problem gets better.