New to the forum but hope you all can help, I have a 1998 chevy blazer 4x4. My water pump went out so I replaced it but after that all that blows out of the any of the vents is hot air. The air will blow from all of the setting, ex. vent, floor, defrost, etc.. As anyone else had this issue or know of a fix. Thanks for all of your help.

 

Did you remove the A/C compressor to replace it? If I recall correctly there were 2 electrical plugs to attach. might be one isn't connected, the system uses a combination of hot and cold air and a lack of A/C could result in a lot of hot air. I've been fortunate not to have to tackle that issue yet.. Only other thing I could think of is a vacuum line knocked off by accident.

 

You may have a problem with the vacuum switch for the temperature settings. There is a service bulletin about the vacuum lines being filled with trans fluid from the transfer case vacuum switch.

It is an inexpensive part that sits on the drivers side of the transfer case on top it is the vacuum source for your 4 wheel drive hi-lo buttons on the dash. The problem may be two fold a: your rear seal on the transmission might be leaking and sending excess fluid into the transfer case b: which raises the level of fluid in the transfercase and the seal in the vacuum switch is bad and letting the excess fluid from the transfercase to get sucked into the vacuum lines of the switch which in turn sucks trans fluid into the vacuum lines under the dash causing the problem you are now experencing....

 

Thanks for the suggestions. I did not remove the AC compressor, but after your suggestion I did disconnect and reconnect. Didn't help, also could not find any loose vacuum hoses. I also looked at the vacuum swith on the transfer case, took off the vacuum hoses and there was no transmission fluid in any of them. I am going to replace it anyway. Any other ideas? Once again thanks for the suggestions.

 

Mine was only blowing hot air also and people were saying the ac probably needs to be recharged so I took it to the shop and they put a pound of frion in there and said it wouldnt take anymore they said it should 2-3 pounds. They said the ac compressor needs to be replaced and other things over $800 for parts and labor. So I'm gonna wait alittle while and have it taken care of.

 

I do not think that it is my compressor, it kicks on while the AC is turned on but still blows hot air. The canister and low end pipe are getting cold as well. I have something about a servo motor in another post. Does anyone know anything about this part. Could it be causing my problem?