My son in law says he sees smoke or steam coming from the vents. It only happens when it rains and when he puts the AC to recirc it quits. I suggested heater core, but he says there is no smell of coolant and does not think that's the problem cause he had the heater core out when he did the evaporator.

 

If the smoke doesn't smell, and it isn't tinged a blue-ish gray color, my money would be on the evaporator freezing up (which could be caused by either a bad refrigerant charge or a malfunctioning pressure switch)- the smoke coming through the vents is the condensation from the melting ice.

I had a similar problem with my '96 Volvo 850, I solved it by always keeping the air circulating andnever usingthe AC at full power for prolonged periods of time. Instead of only smoking when it rained, though, my AC only seemed to smoke when it was incredibly hot outside...the first couple of times it happenedI was sure something important was overheating and I was minutes away from death by explosion (I remember seriously considering immediately pulling over to the side of the road and fleeing on foot). After I started troubleshooting, I realized that I never used the AC unless it was unbearably hot, so those were the only conditions under which I ever observed the AC functioning (when I realized that, I wassecretly a little disappointed, I'd kind of romanticized the idea of sprinting away Mission Impossible-style from a detonatingVolvo). Is it possible your son only uses the AC when it rains?

 

I have never had smoke come out of the vents.

Ihave noticed that when it rains really heavy that the wind shield would fog up.

I would just turn to recirculate and that will usually solve my issue.

I need to replace my cooling fan so right now so I don't have A/C although it does work on the highway. Forced air is the only reason.

I hope that you can solve the problem.


[sm=icon_cheers.gif]

 

What usually happens is the low pressure switch is bad or it goes down a little to low on temp.
The A/C is colder than it is outside so the smoke/steam comes out the vents just like opening a Freezer door in your house.

Mine does it all the time and all my switches are working normally.

Another thing that makes it do that when nothing is wrong if you open the window some when the temp is really low inside the car.

Like a rainy day or really late at night and low fan speed then opening the window to have a Cig.
Not sure if he smokes or not but that will do it.

Or it is freezing up like suggested above. But then the air flow would drop off to almost nothing coming out of the vents.