Blower Speed drops on hills

[Stephen Butler]

Noticed several times that on my STA the interior vent blower speed drops to almost nothing on a hill, then goes back to the correct setting right afterward. Is this normal, or possibly a vacuum leak somewhere?

 

[scott degroot]

Is the blower speed actually decreasing or is it just switching to defrost? More than likely it is switching up to defrost so in that case the vacuum supply to the ac/ heater system needs to be looked at. Possibly a bad check valve or a break in the vacuum line somewhere.

 

[Richard L]

Yep, I agree with l1tech.....sounds like a vacuum problem.



Reminds me of the old 1940's. and early 1950's cars with vacuum operated wipers. I had an old 1950 Ford....step on the gas or try to pull a hill and the wipers would stop running...:bwahaha:



Many of the HVAC control doors are vacuum operated and change/control where the air flow is being directed to...ie floor vents, dash vents, defroster vents, etc. Some of these doors will restrict the air flow from the fan and make it sound like it is changing speeds.



....Rich

 

[EddieS'04]

Reminds me of the old 1940's. and early 1950's cars with vacuum operated wipers. I had an old 1950 Ford....step on the gas or try to pull a hill and the wipers would stop running

Rich,,

so true. I had a '56 ford with vacuum wipers. Realy sucked when it was raining hard..:bwahaha:

 

[Stephen Butler]

Thanks, and I will check to see if it is actually shifting modes. Where exactly is the check valve, and how tough is it to replace?

 

[JohnnyB]

I have been having an issue all summer. Not sure which it is. Where are the lines to the ac/ heater system and the check valve?

thanks

 

[Les C]

Steve, my '10 V6 STA did the same thing on our 1st trip out of town w/3,795 miles on it, it was the A/C vacuum valve.

 

[Stephen Butler]

I checked and yes, it is shifting to defrost when the engine is under significant load, then back to vent...so where exactly is the A/C check valve, and how hard is it to get to/replace?