Hissing noise at heater switch

[Bill Littlefield]

There is a hissing noise coming from my heater/ac switch when I shut the truck off. It may be there when it's running too but it's difficult to tell with the engine noise.



Does this mean the switch is going bad?

Is this a vacuum switch?

Is there an easy way to get to it?

Will it cost me big $$$ to replace?



Appreciate any info you can provide.

 

[Smoker]

It's vacuum probably. Pull it out of the dash and check all the connections.

 

[UKRugbyman77]

AC?

Are you sure it's not just the AC? I noticed mine doing that last night, but I just forgot to turn off the ac before I shut the truck off, (which is a good idee by the way) and it'll hiss like a scorned woman.

Check that out before you get out the sledge and chisel!

 

[Bill Littlefield]

Hissing in all positions

The switch hisses in all positions but I can hear a change in the sound from one position to another. That is how I pegged it to be the switch. After about 1 minute (maybe two) after turning off the truck, it stops. The heater is working in all positions and so is the AC but it appears I've got a leak in the switch. If I don't replace it, it will probably fail completely while I'm on a trip and really need it.



More suggestions?

 

[Extreme1]

Mine's been hissing in the def positions since I bought the truck 4 years ago.

It probably woun't get worse. Check the connections in the dash. You can dissassemble the switch and play with it. If cracked, you might be able to repair with epoxy.

 

[GSchlegel]

Bill,

Mine had started doing the same thing a month ago. Now on a hot day like today the AC wont come out the vents, it comes out the defrost! Its interesting, first thing in the morning while it is cool, the AC works fine, but when it gets hot the vacuum leaks and the air comes out the vent. My dealer said the switch costs $160. 00! I have taken the switch apart, its just a simple slide. I even put a little silicone greese on it to see if that would help seal it - no improvement. I also need ideas and this is the place to get them.

Thanks,

Gene

 

[illflem]

Bill, has your truck had the vacuum check valve recall? My '95s have. If not it's possible that oil has made it to the switch and has partially melted it, just replacing the switch is just short term if this has happened, the whole vacuum system will need to be cleaned out or replaced. Hope that isn't the case but if you see oil in the switch make sure to have it checked out. Someone posted a much cheaper price than $160 for the switch not long ago, more like $30, not sure where they got it maybe mopar for less.

 

[djgwinn]

Hissing noise

Hi, along with the recall for the vacuum check valve, the warranty was extended to 7 years with unlimited mileage. Mine leaks when I put it in the floor position, had the dealer replace the controls at no charge. They had already installed the check valve but it was too late.



David

 

[Bill Littlefield]

reply

Bill F. ,



I did not receive a vacuum check valve recall on my '95. I'll be contacting the local dealer right away to find out more.



Gene, David and others,



Thanks for the info. I'll be tearing into it soon. I hope I don't find oil. I hope it's just a loose connection. It's something I noticed a while ago and it seemed to go away. Now it's back. Probably getting worse since it's persistent this time.