MR2 Roadster Owners Club

The Workshop => Maintenance, Problems & Troubleshooting => Topic started by: Jared on August 26, 2023, 18:18

Title: Heater not working
Post by: Jared on August 26, 2023, 18:18
Hi all
Just had my first MR2 ever and I have to say it's fantastic, had a Porsche before this and this thing is better for out right fun hands down.
I think all is well apart from a few little things but first thing I did this morning was put the heater on but it doesn't get warm.
I have AC and that is working great and the fan speed works as it should just no heat.
Is this a common thing with a quick fix or am I looking at something more of a problem.
Cheers all
Title: Re: Heater not working
Post by: Chilli Girl on August 26, 2023, 18:24
Welcome by the way.  MR2 heaters are excellent so I'm very surprised you don't have any heat.  What I will say is this - make sure you have the vents open as I had mine closed and felt abit of an idiot.  Hopefully this isn't the case with you. ;)
Title: Re: Heater not working
Post by: Dev on August 26, 2023, 19:11
You might need to bleed your coolant system. Sometimes it is a trapped bubble in the heater core.
If you do a search you will see what is required to bleed the coolant of any air pockets.


Title: Re: Heater not working
Post by: Ardent on August 26, 2023, 21:56
as the above 2 posts.
The MR2  heater is excellent. A bit too much in fact.
As above, likely an air lock.
Title: Re: Heater not working
Post by: puma2 on August 27, 2023, 08:22
 :) that is a 1st for sure about lack of heating :o  :o
defo a problem there that needs looking at at :o

the above post are good starter points 8)  8)
Title: Re: Heater not working
Post by: Joesson on August 27, 2023, 12:25
@Jared

As above, the heater is a toaster, so something amiss with yours.
If you have had a look around under the frunk plastics you may have noticed two coils of plastic tubing, these are there to increase the " head" of the coolant when bleeding the heater. If these lengths of tubing aren't available you would do well to get some. Last time I looked B&Q sold tubing from a reel that you cut off yourself. Mine are two 750mm lengths of 9mm x 7mm tube.
Mine were tied up to valves on the heater hoses that are also under the frunk plastics.
Bleeding is a matter of getting the engine up to temperature, putting the heater control to full on, finding some string, fitting your two tubes to the heater tube valves and using the string tie the tubing up under the bonnet. There is likely a " best" sequence for opening and closing the valves, but iirc it is no more difficult than bleeding a central heating radiator.

Title: Re: Heater not working
Post by: Ardent on August 27, 2023, 20:35
@Jared

Well worth getting comfy and hitting the search.

Few posts I recall, the bleeding can go sweet, it can be a git.

And I recall some the air bubble was something in or around the throttle body area.
As above, should be toasty.

I think some vouch for getting the rear end, high as well.
Title: Re: Heater not working
Post by: Jared on September 12, 2023, 15:21
Cheers all, yes probably an air bubble somewhere in the system, although I did get some heat going to work the other morning so I'm sure it's not a big deal but needs to get sorted before winter
Title: Re: Heater not working
Post by: Topdownman on September 12, 2023, 15:57
I would not want to leave it too long in case an air lock would hinder the coolant flow around the engine.
Title: Re: Heater not working
Post by: Ardent on September 12, 2023, 18:12
Quote from: Jared on September 12, 2023, 15:21Cheers all, yes probably an air bubble somewhere in the system, although I did get some heat going to work the other morning so I'm sure it's not a big deal but needs to get sorted before winter
Yep, get that sorted and you will be toasty.
Title: Re: Heater not working
Post by: B_Tank88 on December 5, 2023, 16:24
I have noticed something similar, and also suspecting air in coolant issue.

I only get hot air from side vents. I don't get hot air now from middle or footwell.

I occasionally hear a liquidy gurgling sound for a few seconds after a cold start coming from the HVAC area near the front.

Coolant bleed a good idea?
Title: Re: Heater not working
Post by: JB21 on December 5, 2023, 19:57
I've recently had this with my 2zz and it was a stuck closed coolant thermostat. This is very dangerous as the temp gauge only read a couple of notches above middle/normal even though temps were 120°c using torque pro. If left to go much higher the head gasket would have gone.