tuffluck

iTrader: (4)

it's really weird but i'll be driving and it seems to only happen when i accelerate about 50%, but the AC will stop blowing from the front vents and blow out of the bottom vents, then once i get back to a cruising or lower rpm it will switch to the face vents again. it does this rarely, but in the last 6 weeks has probably happened once a week. i don't understand why...it only last for <10 seconds.

also, the setting on the dash for face/feet vents to be on just doesn't work at all. it stopped working this summer as well, so i'm thinking the two are related somehow. thoughts?

samson_420

iTrader: (1)

All of our AC vents are vacuum controlled. It kind of sounds to me like your switch panel is taken a dump.

BOA279

iTrader: (1)

check the vacuum line in the engine bay...on the firewall, PCM area. If this is cracked or leaking you will have what you describe

wssix99

iTrader: (5)

yep +1

tuffluck

iTrader: (4)

best way to fix it? electrical tape?

01ssreda4

iTrader: (96)

No electrical tape is not the way to fix it. They have all kinds of vacuum patch kits in the help section at the auto parts store.

tuffluck

iTrader: (4)

i'm still a little confused where i am supposed to look. are we talking the right side or left of the PCM? am i looking for a metal or rubber hose? i see like a plastic block to the right of the PCM that has several lines running in and out of it. i don't see any cracks or leaks...is there a good way to test for them? also wouldn't a vacuum leak in the AC system imply i was losing freon, too?

mike171562

iTrader: (4)

I had the same problem and had to replace that plastic bit by the PCM, it had a small crack in it. I bought a bag with like 5 or 6 of them at Advanced Auto for like 4 bucks.

tuffluck

iTrader: (4)

can you take a picture? i am not sure what plastic bit you are referring to. how large is it? thanks for the heads up.

btw, my temperature just did this yesterday probably due or coincidentally because it was the first 95+ day in dallas so the AC was blaring. but it got up to about 225 operating temp, which it has never done. i have never seen it get above 210. and just recently i added a bit more water to my radiator because it was a little low, so i don't think that's the problem. could the vacuum leak cause this?

tuffluck

iTrader: (4)

anyone?

dubga

iTrader: (8)

http://shbox.com/1/4th_gen_tech2.html#HVAC_vacuum

tuffluck

iTrader: (4)

thanks, that link was helpful, but i did test the lines (at least with my mouth i did). the line to the canister under the battery is fine, the line to the intake i can't really test because i don't want to take it off of the brittle back of the intake. but it looks to be fine, and also i've read when that cracks or has a crease in it, the AC blows 100% not on the face vents, so i think the problem is the line that goes to the mode selector. where/what is this line and how do i check it? i see it is going back into the dashboard from the check valve and seems to get very tricky after that. i'm almost thinking it's not worth messing with. anyone else ever have this problem and figure it out? i replaced the check valve and that didn't fix the problem.

fleetmgr

The mode selector is the switch on your dash....you know...the one that says Max A/C, A/C, Defrost etc.