blower fan

I have a 1994 GMC Safari Van, when driving down the road with the AC on, on the level it blows fine out of the vents, but when starting up an incline it acts like the blower switches to the floor as I can feel cold air on the floor. Once the van levels out and runs normal again it comes back to the vents. I was told by a good friend that the Chevy's and GMC's just do that, but it sounds like a vacuum leak to me.

Any ideas, anyone else have this problem??

thanks

Reply to
Pete
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Me too. That's what I'd look for.

Al

Reply to
Big Al

Mine started this just a few months ago. I was told that the vacuum off the manifold controls this. So when you step into the throttle, the vacuum drops which causes the change, I was also told that the vacuum canister hanging off the hood should compensate for this drop in pressure. However, it started happening on my truck when I replaced the compressed hose leading from the manifold to this vacuum canister. The old hose was permanently compressed. I tested the canister and it's holding a vacuum.

Reply to
Todd Copeland

Start replacing vacuum lines, the vehicle is 13 years old, and that engine bay gets mighty hot hoses are probably starting to leak and or collapse. Usually the air goes to the defrosts as that is the default setting(makes sense, clear windshield is important). It could be the engine is getting tired. Compression test called for to determine that. Timing chain could be stretched throwing timing off and as such lowering vacuum, vacuum gauge for that one as well as a timing light, watch for dancing timing, some shifting is normal because of the electronic control, but at idle it should be pretty stable. Find a good exhaust shop to check back pressure in the exhaust system. Also how hard are you pushing it on the highway, or is this an around town occurrence as well.? I have only had one vehicle do this, an

87 S-10 Blazer with a 2.8 V-6, throttle body injection, and only when I was running her bottom off.

Whitelightning

Reply to
Whitelightning

I will start with vacuum lines, its got 115K on it, but runs great other wise, its a V-6 not sure what size. this is around town and alittle highway, to get around here, it takes highway driving to get to where you want to go, ie like the other side of town ( and that could be 25 miles in some cases) anyway, Van runs good, highway driving in never over 65mph, town driving is like 45mph, in some places its hilly, ie the ups and downs that cause the problems with the fan.

thanks all for the input, at least it gives me a place to start looking.

Reply to
Pete

It's a 4.3, its the only one they used. In very early models the 2.5 liter

4 banger was an option, but soon dropped. 115k is just broke in. Check the vacuum line going to the cruise control, it runs close to the exhaust manifold. the hose from the PCV valve goes to pot, usually close to the throttle body. also the vacuum hoses going to the valve on the charcoal canister, both the idle purge line and the control line.

Whitelightning

Reply to
Whitelightning

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