Helen Marie

hi, having a hard time posting, jumped in to ask a question, my 99 has no warm air, blows but no heat., i don't hear any air flow change or noise when i switch to heat nor do i feel heat coming from the rear, any one know where to start looking?

73shark

Welcome to the forum.

Moved to a new thread to get more views.

Don't know if '99s had a heater water control valve but if it does start there. Does the truck heat up to normal operating temp? If not, check thermostat. If it does, then are both heater hoses (in & out) getting warm?

MDTAHOE

Is the coolant full?

Helen Marie

it is,,i bought a book,,im coming back if i cant figure it out,,thanks

kevinkpk

What was asked about the hoses checks the thermostat. After it is warmed up or should be, is the top radiator hose hot, and flowing, you can tell by pinching the hose. Also, with heat selected, does air blow out the bottom, and also defrost to the windshield when defrost selected?

rjcaptsean

Sorry to thread jack, but this is the same issue I am having with a 2001 Sub. Both heater hoses are hot, and the rear unit puts out hot air. The engine warms up to 195 just like it has for the past 10 years. I can hear something moving behind the dash when the temp selector is moved to "hot", but the air coming out of the lower vents and defroster is not warm. It does seem to be reduced flow compared to the "cool" setting. I believe that perhaps there is a selector vent door that is not moving or is blocked.

I searched these forums and elsewhere for a nice expanded (parts diagram) view of the heater unit, but the only one I have found is a pretty lame picture. (No part numbers and it was barely legible. Obviously not a factory diagram.) Is this job going to require me having the freon removed and then pulling the entire dash just to access the heater unit? Anyone have a better link for good parts diagrams? The one in the sticky is permanently closed.

Thanks!

shamrock246

I'm going to replace the doors in mine since all the weather stripping is gone off of them and i get hot and cold air but the volume seems less then my freinds 98 hoe i tried to attach them but there to big ill try in a PM