Hello guys and gals of Pennocks. 88 GT here in a very cool Ontario Canada and my heater will blow hot in Defrost and Heater positions but Vent blows only cold air! Any suggestions would be great thank you. Non AC car BTW

[This message has been edited by 88Fingers (edited 10-24-2025).]

HEATER / DEFROSTER modes can be tempered
VENT mode cannot be tempered, and it will be 'ambient'.

------------------
Original Owner of a Silver '88 GT
Under 'Production Refurbishment' @ 136k Miles

quote Originally posted by Vintage-Nut: HEATER / DEFROSTER modes can be tempered VENT mode cannot be tempered, and it will be 'ambient'.

Oh, I guess that makes sense, as it's literally supposed to just be "the vent to the outside."

I've never seen the control panel for a non-AC Fiero, but I know they had special vents that were controlled by buttons under the dash. I have one of those kits, but haven't installed it in my car yet. I think that option (?) was only available on the 84, but of course, you could get cars after 84 without A/C, they just didn't have that feature.

Oh, okay so it is normal then? Thank you very much for the quick responses guys!

BTW - the slider-type control panel for a non-AC Fiero CAN be 'midway' to 'blend' the heater and the vent modes:

By varying the mode selector between HEATER and VENT, you can vary the proportion of the air coming out the heater and the vent outlets.

Thank you Vintage-Nut. There seems to be some resistance to movement in the sliders and wondered what the fix is for this if any?

quote Originally posted by Vintage-Nut: HEATER / DEFROSTER modes can be tempered VENT mode cannot be tempered, and it will be 'ambient'.

Vent on my non AC Fiero does heat up, it doesn't have as much airflow when on hot as when on cold because of the bleed off to the windshield and floor, but it does definitely send hot air out the vents.

Only picture I could find


It's hard to see, I edited it to show the locations of some things, red is the heater core, solid yellow line is when the lower slider is set to hot, all the fan air goes through the heater core before going to the rest of the ventilation system, the yellow dotted line is it when it's on cold, all the fans air bypasses the heater core and goes to the rest of the system. The vent mode should definitely have heat, and that's how it works on all 80s gm cars I've been in. Vent is just the position, the visible vents that aim at your face, HTR is the floor vents and defrost is the windshield vent.

[This message has been edited by 1985 Fiero GT (edited 10-24-2025).]

Thank you for this information. Appreciate it!

I've always gotten heat out of the Vent's in both AC equipped and non AC Fiero's is your car AC or not, you mention Sliders, so I assume a non-AC car

[This message has been edited by jelly2m8 (edited 10-25-2025).]

Yes it is a Non AC car