306 Heater not getting HOT

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Mon 29 Sep 2003 12:20
306 Heater not getting HOT - hm
Any ideas as to why my incar heater does not get hot (it gets mildly warm)

I confident that I do not have a air lock, or a blockage in the heater matrix.

This has not suddenly happend, it has been like this since I brought the car 3 years ago. never really bothered me, I just put it down to the cool running temp of the car but I no longer think thats the answer and the wife is driving it now so I'm getting stress!

The car runs at 80-82°C on the dash.

MM - you wealth of knowledge would be appreciated.

Cheers

H
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Tue 30 Sep 2003 09:38
306 Heater not getting HOT - M.M
Got to rush hm, elec going off here any minute for whole day.

Taking the usual logical route....

First consider if the coolant feed hose into the heater is at the correct temperature when the engine is warm. The hose should be very hot to touch and the return a little cooler.

If the hose is cool consider a dodgy/wrong thermostat. Check the behaviour of the radiator to see that the engine heats up completely before the stat opens and dumps heat to the rad. If the rad warms up gradually from the time you start the car look at the thermostat.

If you're happy with the stat consider the flow through the heater matrix. I would disconnect the flow and return hoses and flush with the garden hose to prove the flow is free.

If all the above pass OK then is seems your matrix itself is getting nice and hot.

Next look at the heater operation itself.

First are you sure a proper supply of air is able to flow into the heater...not blocked with leaves?

Then think about a linkage fault between the heater dial and the unit...might it not be fully selecting the hot position despite what the knob position indicates? What about a problem with one of the internal control flaps, might it have fallen partially closed?

Lastly I had just such a complaint with a 306 a year or two ago. All the coolant checks passed OK, and apparently so did the heater. But on testing it with the engine off and fan on I noticed the heater casing had split and opened up along its bottom seam within the car, just above the passenger footwell. This was allowing cold air from the fan to blast into the passenger compartment without hardly any going through the matrix.

I had to do the best possible job in-situ as the "proper" repair would have been to remove the whole dash and replace the heater unit assembly...very expensive. Thankfulluy this repair is still fine after 30,000 mls.

M.M

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Wed 1 Oct 2003 15:38
306 Heater not getting HOT - hm
MM,

thanks for the advise,

Had a very quick look last night, (I changed the stat about 9months ago)

1: The heater hoses are hot both in and out.

2: Have checked the blower in car, not too sure what you mean, she blows enought out of the vents, so I assume its not blocked.

3:were would it be blocked with leaves, or the fact that it does blow into the car through the vents a go enough sign?

4:The linkage fault, I go as far as pulling the clock out last night, I could see the wire on the hot/cold dial, as I turned it from hot to cold the wire moved with it freely. Do I have to remove the heater matrix to check the actual operation of the tap on the heater matrix, the old haynes does not show it.

5: not checked for a split in the pipe, but I cay say that when the fans are on flat out I only get air coming the vent that I specified on the dial, I can feel any other air from other vents.

I can only conclude the wire from the dial to the heater matrix is not working correctly, how easy is this to check. Is it a full matric removal?

Cheers

H

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