New guy here with a question...

I have a 2001 Blazer that is my bad weather/beater vehicle. Overall it runs pretty good except for one thing, I cant get any heat. I changed the thermostat yesterday and now I dont even get warm air, it feels like the AC is on. I dont know if its related or not but the controls dont work right either, meaning it only blows out the top. I cant make it go to defrost or down by my feet...is it possible the controls are bad? Would this cause my heat not to work?

 

Are both of the lines going to the heater core around the same temperature? If one is cold you could have a clogged heater core, it is a common issue on these.

 

Ill have to check. Does the heater core have to be replaced or can it be flushed out? Also, why do you think the climate controls wouldnt work?

 

You can flush them out, remove both hoses and use a garden hose to flush both directions. Crap will spew out for a while, when you get good flow and clean water, replace hoses.

The climate control system runs on vacuum, if you have a bad vac line, no worky. Also if any ATF has worked it's way into the control head from the transfer case it can screw them up.

 

Manual HVAC or automatic climate control? Diagnosis is different between the systems. The HVAC actuators under the dash control the airflow, and they are vacuum operated. If you can't change where it comes out, it needs to be diagnosed, possibly a vacuum problem. If the slave door is shut, all airflow will bypass the heater core, and you will not get any warm airflow, no matter where you set the temperature. The temperature blend door is electronic.

 

Yeah they are manual, sorry for the confusion.

 

Near the front of the power brake booster,
there should be a connection with some
vacuum hoses. This image might help: