My '85 MR2 which I just purchased has absolutely no heat whatsoever.
I thought that it was probably because the '85-only automatic control system had a wiring issue somewhere, preventing the blender door from going to the "heat" setting. But I took apart the dash today and was able to observe the flapper doors moving back and forth as I moved the slider switch from hot to cold:
The vacuum-operated coolant valve in the "frunk" seems to be operating properly. It opens and closes the valve with the movement of the hot/cold slider switch anyhow. And it only starts to do this after the car is warmed up, which I believe is proper.
This thing only has 34k on it, so I'm ruling out a clogged heater core. And even if the core was mostly clogged, I would still be able to discern some change in temperature out of the vents. But there's never any change - it's like the thing is on full cold always.
So I'm wondering if there is some other inconspicuous blender door in the system which I am unaware of.
Does anyone know anything about this system?
Is there any way you have air in the cooling system?
I guess it's possible. The heater core lines run under the car and then up to the core which is on the "frunk" wall. I will try to bleed that loop and see what that does.
spitfirebill wrote:
Is there any way you have air in the cooling system?
Considering that the MR2 has like a county mile of line to and from the radiator it wouldn't surprise me. They're supposed to be notoriously hard to bleed.
At least second gens are impossible to bleed if you don't follow the procedure in the manual. I'm guessing 1st gens are probably the same.
Yes, there is a detailed bleeding process for gen1.
If you do not have the Big Green Book (factory service manual) then www.mr2oc.com should lead to to a written, detailed description.
Feel the lines in and out of the core. Both should be hot if you have flow. Maybe the valve or blend door is broke and the lever moves but the guts don't?
My guess also is air in the system. It is involved getting it out.
ZZW30s are wickedly easy to bleed, they even include a special service tool that's already connected and ready to use. There's a knurled knob to turn and open the bleeder in the front. Once you remove the frunk surround, it's a zero tool job to bleed one, use the supplied tie wrap to afix the pre-installed hose to the hood open the valve and idle till bled. done.
