AC/Heater selector switch problem ?

[basstracker]

Greetings.

New to this forum. We have a 98 Astro. Wife said the air is not working, I checked it out and the air works but I cant get the vents to come on. Im not sure if the selector switch is messed up or if its a vacum problem. Its stuck in the defrost position. Any suggestions? Last month I replaced the fan switch because the high speed wouldnt work. It worked fine for a few days then lost highest speed again so not sure if this is part of problem also or not.

Thanks all.

[John72]

There are several threads regarding this issue. Type "vents" in the search box and you will see them. Most all of the replies concern vaccum hoses/tubes. I have the same problem with my 2000 GMC Safari and plan to check it out tonight.

[basstracker]

Thanks. Found the stuck vent problem readinng the posts, vacum line, replaced it tonight, vents work again. Now to research the blower motor only running first 3 speeds. (switch was replaced)

Thanks agian!

[John72]

Originally Posted by basstracker

Thanks. Found the stuck vent problem readinng the posts, vacum line, replaced it tonight, vents work again. Now to research the blower motor only running first 3 speeds. (switch was replaced)

Thanks agian!

Glad to hear it. I had to repair my lawn mower last night, so I didn't have a chance to look at the van. Maybe tonight. I have a guess on the blower. I recall some vehicles in the past having "high blower relays". Any chance the Astro/Safari would have such?

[basstracker]

I took out the washer/coolent tanks, tuned on blower switch to high, moved a plug up and down and it took off fine. This plug has like 5 wires to it, located low and below blower motor under hood. Cant get to it with out tanks out. Not sure if this is a relay or not, but it was loose.

We'll see how long it lasts till I hvad to play with again or replace the plug maybe.

[louu]

I am an owner of a 1998 Chevy Astro with rear heat and rear air. My problem was only cold air out of the rear heat and only the front defrost vents worked and the temperture selector not switching for hot to cold. I will try to be as detailed as possible. Lift the hood, and look at the large black box on the top left side of the engine. Just behind the AC reservoir, there is a vacuum line attached to the large black box on top right side, that looks like a Tee fitting with three connections. One went to the float switch on the bottom right of the larger black box near back, the other goes straight down to the vacuum ball located on the frame of the vehicle (underneath). The last is a thin vacuum line that looks like an electrical wire. Pull on all three lines one at a time. If one pulls all the way up to you, that is the broken one. The thin vacuum was broken in half on my Astro. The fix was to remove the air filter tube (the 3" flex tube that goes to the backside of the air filter box). Once removed, look for a flexible black tubing about a 1/2 inch round that should look empty because your line is broken. Pull the tubing to reveal the other half of the hose and reconnect with tubing that will fit over the thin black wire. Not sure what size, but what I did notice is that this was probably the same problem that GM fixed before when the vehicle was under warranty because my line looked repaired but was broken in a different spot. Before I reinstalled the air box tubing, I did wrap the entire flex tubing line with aluminum foil to help block the heat. I am not a professional, but I tried this and it worked for me. Good luck. This. feels like the scene in Independence Day when they figured out how to bring down the spaceships in the sky. Good luck

[John72]

I was finally able to look at my 2000 Safari. It's going to be 90 this week and we will need that AC. I couldn't see anything from the front of the van so I removed the engine cover and looked from inside. I could see a 1/8" tube on the right side (passenger) going downward towards the alternator. I gently pulled on it and it broke. The tube also went to the left in front of the throttle body so I gently pulled on it and it broke off also. The broken piece was about 6 inches. I replaced it with an 8 inch piece of rubber vaccum hose to connect the remaining tubing. The AC blows through the vents like brand new. Now that I know the location of the tubing I could probably do the fix from the front of the van without removing the engine cover.

[mbstang]

I just fixed this same problem this morning on my Astro, thanks to everyone whos posted the solution to this, I work out of the van all day and it will be nice having the air out of the vents again, I took some pics to show the location of the vacuum line in question

engine side, drivers seat perspective with engine cover removed...



Engine bay, behind the ac accumulator, passengers side of vehicle



Hope this helps someone

[astro44]

I also have a '98 and had to do the same repair on the vac hose. Now I'm having the same problem with the switch. It will not work on high. Did you ever find the solution ?

[Bradak]

Thanks Guys!

I bought the gm oem hose before looking for a crack. Such a cheap part, may as well have it before opening up the doghouse. Seems the loss of vent control is related to a broken vacuum line in the engine compartment 90% of the time. Just before removing the doghouse, I had a close look from under the hood and actually saw the almost broken in half hose right above the port where the upper rad hose leaves the engine. If you look closely with your head low against the top of the grill, you can actually see the boot connection on the rear end of the hose.

The boots on the barbs were a bit of a pain, until I cut them with a sharp knife. Was careful not to cut the plastic male barbs.

It's great to have the hot air blowing in my face again!

Brad