90Maxima

OK, heres the situation

The heater in my 90 GXE wont blow hot air AT ALL! All the components i know about are good. I just replaced the core AND the thermostat. nothing. Checked for clogs, nothing. and I know the pump is good, also checked the heater control valve, good too. Blower works. now get this. When i slide the temp bar to cold(after disabling the hcv), the hoses for the core get MAAAD hot, but absolutley no heat inside. THEN, when you put it on heat, the hoses cool off, and STILL no heat. I have absolutley now idea what to do now, any suggestions. Im freezing my @$$ off down here and i needz some heat.

ninezero

You put in a new heater core or a used one,maybe its blocked inside?

tmuscedere

One step at a time,

Does the lower heater core hose get hot? Or is it just the upper getting hot?

CHIMAIRA90

I'VE GOT THE EXACT SAME PROBLEM ON THE EXACT SAME CAR! my heater SUCKS! i've got ICE cold a/c. but when it comes to heat, BLAH. i got a new thermostat, and it didnt do ANY good. please help! it's gettin cold down here. oh yeah, and my temp guage will go to ½ way when warmed up...then i'll turn on the heater and the guage will drop to cold and blow cold air. BOO!

mtcookson

iTrader: (2)

check your radiator cap. mine did the same thing. my radiator cap was bad so it wasn't holding any pressure at all. you could get the engine really hot and pop the cap off and not get any steam buildup. i would check and see if that is bad. be very cautious though, if it is good and you pop that thing off when hot steam will go everywhere and could cause serious burns. be really careful.

90Maxima

I thought it was the cap, and turnes out it was bad, but I replaced it and still nothing. Both core hoses get hot when i have the AC on. BUT the top hose is the only one that gets hot when the heat is on.The temp gauge stays at the middle no matter what. I now the heater control valve works, and i know theres no blocks in the core(tested it)

Now one thing i did notice is that my fans dont come on 99% of the time. the engine just runs cold, wich i thought was kinda wierd. I know they work cuz they came on the other day when i tried to bleed the cooling system, but with full level it runs cold, no matter how hot it is.

Now i was thinking, maybe I have the hoses(I really doubt it, but im so desperate for ideas) backwards, anyone have proper pics of the core at the firewall?

tmuscedere

the upper hose is the one that comes from the vacuum valve. The lower hose is the one that comes from the engine directly. Right beside the vacuum valve there is a clip that holds both heater hoses. The one that goes to the lower heater core sits in the lower part of the clip. the lower heater hose goes to the engine if I remember right next to a bracket that holds some relays.