Heater Matrix/Rad - No hot air.

Cass · 11-12-2014 11:14pm #1

Bit of a long one, but i'll try and shorten while keeping all the details necessary.

I've spent the last couple of days sorting, or at least trying to, out an issue with a MK I Mondeo. It's a 96 1.8 tdsi. With the colder days my sister (owner of the car) noticed the heater would not clear the front windscreen. It only blew cold air. It got to the point where she would be driving, the windscreen would mist up and nothing would clear it meaning she was essentially blind. A hazard for driving.

I checked the usual suspects and the fan, controls, etc are all working. The only issue is no heat. As i went to get under the dash i noticed the floor was soaking wet. I mean soaking. To me that signified a leak in the system and as it was inside i immediately thought of the heater matrix/rad. I stripped out the glovebox, centre console, and side coverings. It gave me access to the matrix without having to remove the entire dash. A few scraps, cuts, and some cursing later and i have the matrix out. I have before this disconnected the battery and tied the pipes from the header tank into a loop to cut off the matrix.

I poured water into the matrix and it emptied through a hole almost immediately. So i ordered one online and a new thermostat (as it was cheap and an easy fix to resolve a further possible issue). I fitted the matrix and thermostat, but noticed the header tank was only down a small bit from the max level, but assumed it would drop in level when i ran the engine to check if the matrix was now working. It only dropped about half a pint. However after 25 - 30 minutes the car was still blowing cold air. It was late so i finished for the night.

This morning i took the pipes off and connected up the water hose. I blew the system out until the water ran clear (there was a lot of dirty/rusted colour water). I then done it in reverse (water in the out pipe) and again ran it till the water ran clear. I then ran it through the pipes from the header tank. All was good so i filled the tank with the proper coolant/water mix/solution. Started the car and ran it for while.

I now have warm air. Warm being the key word. It's barely lukewarm which while an improvement is not fully working. The air should be hot. I checked the pipes and everything that should be hot is. So hot you cannot keep your hand on the pipes for too long. So the coolant/water into the matrix from the engine bay must be hot, but that heat is not getting into the car in the form of hot air.

I done all this with the header tank cap on. I'm wondering is the system somehow airlocked. Not enough to stop it functioning, but not clear enough to let the matrix heat up sufficiently to blow hot air. I intend to run the car in the morning with the cap off, massage the pipes to work any air through, but i'm wondering if anyone else has done this and if so are there any "speedbumps" i have missed or should be aware off.

Lastly, thank God says ye, the thermostat i got has an opening temp of 87. The original one had a temp of 92. I checked both of these with hot water, measured with a digital thermometer. Would this be enough to cause the difference between hot and warm air? Would the system need flushed again? Have i missed anything?

Any help, advice, guidance would be appreciated to save me having to do the same task multiple times needlessly/repeatedly.

Thanks in advance.

greasepalm · 11-12-2014 11:23pm

even though its only a few degrees it is not getting hot enough to get warmer air into car as stat is opening sooner,also recheck any tap or flap shut off meaning some cars have water flowing into matrix all the time as no heater tap and switching heat on or off is by moving flap,is it moving correctly on/off?

Cass · 11-12-2014 11:43pm

greasepalm wrote: »

even though its only a few degrees it is not getting hot enough to get warmer air into car as stat is opening sooner,

I've been arguing this point with myself and the old thermostat works so i was going to stick it back into the car to see if it made a difference. The only reason i haven't done it yet is, like you said, i convinced myself that 5 degrees wasn't enough of a variance to cause the issue.

However with pretty much everything else exhausted it seems the most likely cause.

also recheck any tap or flap shut off meaning some cars have water flowing into matrix all the time as no heater tap and switching heat on or off is by moving flap,is it moving correctly on/off?

I believe (famous last words) it is working fine. However will recheck to make sure.

Cheers.

Cass · 12-12-2014 1:30pm

Right, i've replaced the new thermostat with the old one. Both were opening at roughly the same temp but the old one at a higher temp and i noticed (not sure how i missed it before) that it opens about 2 times more than the newer one. So it seems the new one was not the right one.

Replaced the thermostat, and took the cap off the header tank. Ran the car and after a few minutes the thermostat opened and the level of coolant dropped. I topped it up and there was a lot of air during this process. So i'm happy rthe system is flushed and bled of air.

I checked the pipes from the rad, to the matrix and both were hot. I turned on the heating in the car and all i get is arctic cold. The little bit of heat i was getting is gone. I've checked the fan for the blower and it works fine. The directional dial works as it changes from windscreen to face/cabin, to feet, etc when set. The only thing i can think of is the temp dial. While it turns, and the cogs and metal rod move i'm wondering is it actually allowing the hot air (that must be created by the matrix as the pipes are hot going into and out of it) into the cabin.

The accumulator and vacuum i'm assuming are working fine as the direction is working fine so this is really my only other avenue to check.

Cass · 12-12-2014 6:26pm

Think i have is sorted.

Went through all the systems today. Vacuum pipes, heater pipes, the matrix, etc, etc. Nothing. Got the warm going but by no means hot and when i turned the fan on it seemed to get colder.

Out off annoyance i said i'd check the pollen filter. Lifted the compartment panel and guess what, no pollen filter. I've since found out that a few days ago my Father took it out to clean/check. It was so bad he left it out. However he never told me, never replaced it and as such the car is sucking in the freezing cold air from outside which the heat of the rad cannot match/overcome.

I've a new pollen filter ordered and have the battery on charge (another issue i have to fix). I'm hoping when the pollen filter is in it'll block 90% of the cols air that is currently barreling in from the outside and allow the heater to do it's job fully.

Will update as i progress.

Cass · 13-12-2014 1:49am

Obviously i haven't gotten the pollen filter, but it was bothering me so i "improvised".

I cut a piece of foam the size, length and depth of the pollen filter compartment. I placed it into the compartment and took the car for a drive. 5 minutes up the road and back again. Engine reached it's normal driving temp. and i had hot air. When i cycled through the fan settings it did not get colder, it stayed hot.

What a PITA the whole excursion was and the killing part was everything from today was completely unnecessary simply because when i asked i was told "i changed the pollen filter" which actually meant i took it out and left a big gapping hole.

:rolleyes:

So hurrah. Success. When the pollen filter goes in it'll do the same, if not better, job.

Anyway hopefully all this will help someone out there. There are so many systems/instruments related to the heater it can be annoying to nail one down especially when you think it has nothing to do with it.

Thanks for allowing me to bounce ideas of people and think out loud. :cool:

Harcrid · 13-12-2014 12:57pm

Nice job. A lot of hard work but at least you figured it out in the end. It would have been frustrating if you didn't find the cause.

iano.p · 13-12-2014 1:05pm

Didn't think a pollen filter would do that. Will try the van later and see I only have cold in it too.

greasepalm · 13-12-2014 7:26pm

see what ya started now they all want heat in their vehicles lol,great result.

Cass · 17-12-2014 1:29am

Harcrid wrote: »

Nice job. A lot of hard work but at least you figured it out in the end. It would have been frustrating if you didn't find the cause.

Ya can sing that. "Fixed" the electric window on my jeep, without knowing how i done it. Still bothers me to this day.

iano.p wrote: »

Didn't think a pollen filter would do that. Will try the van later and see I only have cold in it too.

As per the posts above it was not only the pollen filter, but too many people overlook it. It serves a few functions other than filtering the air into the cabin.

The pollen worked, and while it's not as hot with the filter in instead of the foam it still gives warm/hot air. My sister says it's not as hot as before, then i gently remind her the fix cost her nothing, she had a leaking rad/flooded car before, and suddenly all is right with the world.

greasepalm wrote: »

see what ya started now they all want heat in their vehicles lol,great result.

Fussy lot aren't they.

I've seen about 10 or so threads over the last week or two asking similar questions. People are only now looking to their heaters due to thee cold weather, and it's now that any faults will show up.

iano.p · 17-12-2014 7:52am

I already changed the matrix in the van still nothing. I got the filter yesterday and the old one had a big hole in it. So its working better than it was anyway thanks

greasepalm · 17-12-2014 11:17pm

check your heater pipes as they should be hot that you cant touch at engine running temp,either a flap or tap is not diverting heat,is it full of coolant and bled if need be?

Cass · 17-12-2014 11:25pm

As said above i flushed the entire system before "closing up".

You need to disconnect the in and out pipe leading to the matrix. Run water in, not too high a pressure, through the in pipe until it runs clear. Then run it in through the out pipe. This ensures any blockages are moved. Again the water should run clear and at the same pressure the it's going in at.

When you have the system bled reconnect the pipes. Take/keep the cap off the header tank. This is necessary as the levels of coolant/water will drop as the van heats up, and don't forget to check the heat of the pipes and don't be afraid to "massage" the pipes. You'll see the air bubbling back into the header tank. When the van has reached running temp, and the thermostat kicks in check the coolant/water level (really keep an eye on this as if you miss a big drop you may have to bleed it again) has not dropped too low. When up to the proper level and the van is running well close the header tank cap.

Take the van for a drive and check the heat when driving. This all sounds like a lot of work, but really it's only a 30 minute job. The flushing out should take a few minutes each way, and the running of the van/topping up coolant levels should take an additional 20 minutes.

pablo128 · 20-12-2014 11:13pm

There's an electrical unit on the heating system on those Fords near the bulkhead which gives trouble.I think it's called a heater control valve or something. They used to give a bit of trouble back when I worked on them.

greasepalm · 20-12-2014 11:18pm

they still do give trouble done 4 on fiestas and think one needed heater control as hot air all the time lol.

Heater Matrix/Rad - No hot air.

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Forum Charter - Useful Information - Photo thread: Hardware - Ranges by County - Hunting Laws/Important threads - Upcoming Events - RFDs by County

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Forum Charter - Useful Information - Photo thread: Hardware - Ranges by County - Hunting Laws/Important threads - Upcoming Events - RFDs by County

Forum Charter - Useful Information - Photo thread: Hardware - Ranges by County - Hunting Laws/Important threads - Upcoming Events - RFDs by County

Forum Charter - Useful Information - Photo thread: Hardware - Ranges by County - Hunting Laws/Important threads - Upcoming Events - RFDs by County