I have a 1989 max and the heater doesnt blow hot air ,i just put in 180 thermostat and car temp looks aroung middle on the gauge heater is set all the way to hot,i made sure compressor is not running any help would be great as it's going to start getting cold here in oregon.

 

You need to bleed the air out of the cooling system (very common issue with the vg engine after you open up the cooling system)

When engine is cold:..Jack up the front end as high as you can get it(atleast 2ft. if possible)/remove radiator cap/start engine,let idle while you are constantly topping off the radiator as it is running,until it will hold no more..

Note: you need to do this procedure until the the engine temp needle is close to mid way(yes,sometime during the process,coolant will "burp" out of the radiator,this is normal,it is the air bubbles in the cooling system coming to the top,and out of the radiator)

 

the engine temp is getting plenty warm that hot air should be blowing out of vents,it didnt blow hot before replacing stat either thats why i replaced stat ,figured car not getting warm enough.Something must not be right with heater or something when putting it to heat mode it must be staying in cooling or outside air or something in vents not switching the right way,i dont know very confused.The engine temp gets very hot now but air is ice cold blowing out ,ac comp not running.anyone

 

Do you have manual or auto climate control? and did it just stop working abruptly or gradually over time?

 

sounds like its time to flush the coolant system and check the bypass valve.

 

heh. could be water pump going (hasnt GONE yet). not very descriptive about the problem...

 

is the heater valve more prone to stay stuck open(hot in) or closed (no water in?) have some one switch the temp slider from full cold to hot while
looking at the valve arm around where the middle of the firewall is also

 

do what green said and bleed the air first, 95% sure that is your problem, then post back if that doesn't work

 

Oh check the floor on the passenger side. See if there is coolant in the carpet. If so. Heater core is done.

 

or heater core could be clogged

 

+1 to bleeding air out of the system. It is almost always the issue with VG's. I've been using this method for several years.