Cleaning evap core for better a/c function

[jb1016]

Mods: Can we make this a sticky?

First off, props to the guys on the FSC forum for this thread, and to IndyAnne for posting a link to it. But I figured it might help some more people get the most out of their a/c if we had a thread dedicated to it here. My a/c was working pretty well already, but I have always wondered if it could be better. So I decided I would clean my evaporator and post up some pics. My truck is a 93, so hopefully in the future somebody with a 95+ will post pics, since the process is slightly different for the different dashboards.

So you start by taking off the glovebox door and taking out the glovebox liner. The liner is held in with 7mm screws -- you'll need that socket a few times before you're done. Now you should see this.



The silver box on the far right is the ECM; it's clipped onto a plastic tray. All you have to do is grab it and pull to the left and it slides right off the tray. I unplugged it to get it out of my way (I disconnected the battery first). Next you have to get the tray out of the way. There are two 7mm screws on top in the back. They weren't very hard to get out for me. The one on the right is kind of down in a hole, and tougher to get to -- I was worried because I couldn't get my ratchet back there -- but it wasn't in very tight, so it was no problem to just turn it with the socket and a short extension. Once you have those two screws out, the tray should just lift right out. There are two more screws under the tray, but the tray just rests on them, and I didn't have to loosen them to get mine out. Those two screws are visible in this next pic on either side of the black electical connection.



Now you're looking at the blower motor housing. At this point, if your truck has one, remove the courtesy light mounted on the bottom of the dash under the glovebox (one 7mm screw). Unplug the two electical connections to the blower motor. Now the housing cover comes off. It's soft-sided and isn't attached to anything; it just fits over stuff. Here's a picture of it out of the truck so you can see what I mean.



Now, you're ready to disconnect the hose, undo five more 7mm screws (you might actually need the ratchet or a driver handle for these), and take out the blower motor. It's a tight fit, but it will come out from under the dash without breaking anything -- it's all in the way you turn it. In this next pic, you can see that the top side it flat-shaped; that's the side you want up, or else it won't fit. Pull the hose out from under the dash first, and then pull and wiggle until the whole motor comes out.

[jb1016]

Now you can get to the evap core. It's inside this hole, and to the left. The second pic is looking up and to the left, from the floorboard.





You'll be able to reach back up in there and start pulling stuff out...I didn't get very much compared to some of the guys on the other forum, but there was still some trash/leaves/etc in there that I was able to get out with my hand. I also used a toothbrush to scrub the core and reach back into the farthest corners.



After that, some of the guys on FSC said they used a garden hose, or the low-pressure hose at a drive-through car wash, to spray off the core. If you do spray it with water, most of it should drain out the condensation drain, into the engine compartment and onto the ground. Just take it easy with the hose, or it will be too much water for the relatively small drain hole, and you'll end up with water all over the floor of your cab. They said to just keep rinsing until the water coming out turns clear. I decided not to use the hose, and I went with some foaming, self-rinsing condenser cleaner, which I got at Lowe's. I just sprayed it back in there as best I could, and let the foam do the rest.

After a few days, I have to say that while the volume of air coming out the vents seems to be the same, it is colder. So it helped some, and all it cost me was about five bucks for the can of cleaner (totally free if you use the garden hose) and it took me about an hour and a half, top to bottom. Hope this helps somebody else!

[Boog]

Thanks for posting this up JB. This is timely since I have been wondering if this might help my 97 Burb where the front air is not as cold nor is the air flow as strong as the rear air.

[k5hart]

Great write up. I'm planning to do this when I have the dash out to replace it.

[jb1016]

K5, there are pics on the other forum of somebody who did his with the dash out. In his case, the PO of the truck owned a dog -- the pics of the evap core are unbelievable. It had enough hair on it to make a wig.

[k5hart]

I wonder if mine is the same way. I don't have the air flow I think it should. The previous owner of mine had a lab that he carried around. You should have seen the amount of hair under the back seat! I'm amazed my interior is in such good shape considering the dog.

[ChevLoRay]

With that info and the steps listed, maybe this pic will also help.

[jb1016]

Looks like the 95+ trucks use the same blower motor.

[70BLAZERX2]

Another hint/tip toward colder a/c out the vents..While your system is apart,simply change the "orfice tube" that goes inline on the low side hose. There is a dimple where this is located,usually with a 3/4 and 7/8 in nut up by the firewall. near the drier.

If you change it out,stock gm one is around 1 - 2 bucks.

Get one for a 92 Ford Crown Vic. This is a little smaller of a restiction and this will get you in the 20-35 degree range of a/c temp at the dash outlet.

I worked for a caddy dealer years ago...and the climate control would not let it get that cold,well after the 1st 3 customers i did this to there caddy...they would all say they would have to turn it off it got to cold..then i was swamped with a/c work for years. Untill i moved from Delaware. .If you like cold a/c..this will help you out..cost 2-3 bucks for the tube. any parts store.

[ChevLoRay]

That's good information, right there....I don't care who you are.

[hatzie]

http://www.fullsizechevy.com/forum/g...ove-obs-c.html
The link in the first post has moved.

[Boog]

I'm glad you brought this back up Hatzie.

[jb1016]

Thanks Hatzie!