OBS Evaporator Case

OUMike · June 10, 2005

okay...so I gotta 94' 4.3L Rado. AC works great in all temps but eventually I get a drip from under my evaporator case. This appears to be condensation because it starts to do it after the AC has been on a while. At first it dripped from one spot. Now I think its dripping from two.

I highly doubt this has anything to do with blockage in the case because I've had it blown out a couple of times with air compressors and no such luck. Has anyone ever taken on of these cases apart themselves? Do I have to drain/recharge the unit when I do this?

I really don't wanna pay "earl" $450 to do this work like i've been quoted. Everyone wants to replace the evaporator. AC works good, so I really don't wanna do that.

Thanks for the help.

macifre · June 10, 2005

I do not know excactly this case itself, but we do see a lot of automotive A/C systems here. Usually when you get some kind of driping after a little while of A/C usage its because the drain hose from the evaporator case inside the cab going out just about the passenger side close to the firewall gets clogged. What happens is that dirt keeps clogging the drain hose until backpressure is built, you get a little wet spot on the carpet that can keep growing to a big mess if the problem goes untreated. I can be positive that your problem is not about an evaporator blocking of ice build up because you would see that after having the A/C working a while you would stop getting airflow from the vents and it would leave a big spot of water in the parking space after being blocked.

You can deffinetly do it yourself, and opening the black box inside the cab does not have anything to do with opening the freon sealed system. Inside you will find the evaporator itself (possibly very dirty) with the thermostat attached to it and at the bottom of the box you will find a drain with a hose leading its way towards the other side of the fire wall, you have to thoroghly clean dirt because of the evaporator getting wet while cycling on and off the a/c system this dirt turns into some kind of "mud" that ends up clogging the little drain hose....

Give it a try, just be careful of not bending any tubes....

Let me know of the outcome...

OUMike · June 10, 2005

I do not know excactly this case itself, but we do see a lot of automotive A/C systems here. Usually when you get some kind of driping after a little while of A/C usage its because the drain hose from the evaporator case inside the cab going out just about the passenger side close to the firewall gets clogged. What happens is that dirt keeps clogging the drain hose until backpressure is built, you get a little wet spot on the carpet that can keep growing to a big mess if the problem goes untreated. I can be positive that your problem is not about an evaporator blocking of ice build up because you would see that after having the A/C working a while you would stop getting airflow from the vents and it would leave a big spot of water in the parking space after being blocked.

You can deffinetly do it yourself, and opening the black box inside the cab does not have anything to do with opening the freon sealed system. Inside you will find the evaporator itself (possibly very dirty) with the thermostat attached to it and at the bottom of the box you will find a drain with a hose leading its way towards the other side of the fire wall, you have to thoroghly clean dirt because of the evaporator getting wet while cycling on and off the a/c system this dirt turns into some kind of "mud" that ends up clogging the little drain hose....

Give it a try, just be careful of not bending any tubes....

Let me know of the outcome...

<{POST_SNAPBACK}>

Sounds great. I actually tried to do this once, but I'm not sure why I coudln't get the case off. How many screws? Is there anything special I need to know?

macifre · June 11, 2005

Nothing special that I know of, I beleive it has some kind of clips holding the box together but I haven't worked on any truck like that for a couple of years...

Just be careful when loosening the screws, don't take them out one by one because it is harder to get the last one out, rather loosen and then take them out..