Heater not blowing hot air ?

[Newcastle knight]

Hi all,

Ive just noticed my heaters are blowing luke warm air at best even with it set as hot as it will go. ive checked the slider and its working and opening to the door infront of the heater matrix. Both hoses going to and from the heater matrix heat up so there is hot coolant going to it, so im a bit confused ?

i played on in the garage with it for a bit, it seems to be a bit warmer if i set it to blow the air out of the vents facing you, but its the defroster vents i need it on the most to demist the windscreen if i get caught in the rain or whatever.

[SUPERCHARGEDGTA]

is the temp. gauge showing warm?
could need flusing

[Newcastle knight]

yeah i let the car warm up as it does, it had been running a good 15 mins while i was faffing on, and with the heater blowing the temp was keeping at a steady 180-190, then when i switched the heater off it started slowly climbing a bit more.

i flushed the whole system about 2 years ago, its got a new thermostat which is working, so everything should be flowing around ok, and the heater matrix itself was replaced about 4 years ago when my old one crapped out.

[G20BlazerTA]

Could it just be that the controls that turn the heater from cold to hot are not working as they should ? Don't know how they work on an 87 though,are they cable or vacuum operated. But it might just be that although the heater control on dash is in the hot position the heater itself is only set for warm. I see the AC has been removed on your motor. Don't some AC cars use vacuum instead of cables to open and close flaps etc to direct airflow to vents,defrost outlets etc.

[Newcastle knight]

Yeah its nearly all vacuum operated, apart from the Hot/Cold setting, thats on a cable, ive got the under dash plastic removed at the minute and i can see its working when i move the slide, the arm is going backwards and forwards and i can hear the door infront of the heater matrix moving so its definatley working

[G20BlazerTA]

How strange. As you say it seems to feel a bit warmer when set to blow air out of front vents maybe it is a vacuum control problem,ie,the air is not being directed where you want it but being bled off to more than one set of vents at the same time.
Only other thing i can think of is some of the ducting under dash might be loose or not attached to defroster vents. I know when I restored my 81 Blazer a lot of the heater air ducting under dash was loose and/or had bits of factory fitted foam seals between the ducting missing. Made hell of a difference when I sealed up all these air leaks

[ccckeeper]

Have you tried bypassing the heater valve, guessing it may not be opening properly.

[Newcastle knight]

not sure what or where a heater valve is ?

[Retro]

I had this problem twice. Both times it was a fault with the heater control panel. Mainly the heater selector switch itself!

[Newcastle knight]

I sorted this, totally forgot about this thread !

ok, ive got no heater valve, and turns out i had an extra hose going between my feed and return line to the heater core ! so i deleted that and now i have hot air again so i can demist the windscreen, the blowers are still naff compared to modern cars but hey what can you expect.