Sorry for starting another heater question. My heaters aren't hot, just blowing cold air.. I've done the research and used the search and found some answers I'm after, but not all. I've recently changed the coolant, thermostat, added some good bypass valves and renewed some brittle hoses. The car apparently had a new matrix fitted in December. I've left the car running with the header tank cap off and squeezed all the pipes until no more bubbles appear. All pipes are red hot; including those going into the bulkhead for the heater. Carpets are not wet and no water is being lost... But I still have cold air blowing. Now my bypass valves are: Alloy valve on the left hand side to the bulkhead from the metal pipework and then the plastic valve on the right of the bulkhead to the plastic flange on the side of the head. Are these the right way around? Also, if my heater flaps have broken, can these be fixed or replaced? Or will I need a new heater unit - If so where can I buy one? Could my new matrix be blocked after only 3 months!? Any info would be greatly appreciated.
id lose the bypass valves , not needed with a new matrix try running a hose both ways through the matrix to see if it flow
Will try the hosepipe trick this weekend.. Do you think some Forte flush would be worth a shout whilst I'm at it?
id be very surprised if a new matrix is blocked does any thing look like its been disturbed latley? feel the hoses and see if heat is going in and out
All of the pipes are red hot.. Even the ones coming in and out... I'm suspecting airlock or broken heater flap.. Do you know which way the bypass valves should be?
No the matrix isn't plagued by the old problems. Mine didn't work until I removed the valves. Now its like a sauna.
22mm copper pipe is what you use to replace the bypass valves and no worries with a new matrix as it is probably a mk3 item not a mk2 so the valves are surplus to your requirements
Thought as much... That may be why it's cold... Thanks boys.. I'll get some new pipes on order for what it's worth.
Another problem people have reported is the foam that surrounds the matrix breaks down so air doesn't flow directly through the matrix but rather around it But swap/remove the bypass valve first
I've had loads of issues over the last couple of years, the first thing I did was drill out the waxstat in the metal valve thinking this was faulty (and yes that should be on the right) the plastic one is just a return with nothing in it. This didn't cure it and the pipes were hot into and out of the bulkhead. Assuming you've not got a massive air lock, as I did just this weekend, which as has already been said can be cleared with a garden hose (once you've got the valves on correct or got rid of them) then most likely is the foam. But it's not on the matrix, it's on the flaps (3 if I remember) which perish over the years and eventually and subtly blow out through the vents. This is what happened to mine and after trawling the internet on what to use and how to do it with my average knowledge I gave it a go. I bought from a plumbers merchant the silver tape (identical to gaffer tape) they use behind radiators. That was about 5 a roll and is way stickier and withstands far higher temperatures, and as yet its been fine. You can do the job either partially taking the lower section of dash trims, glove box, centre console etc out but you will need to be very dextrous with the tape and hands and be prepared to keep trying to wrap the tape around, or you can take the dash and heater box out completely and do it in the warmth of your house. Either way I hope that cures or at least helps. There's a couple of really good pictorial threads on here somewhere which might help.
How do you clear an airlock with a garden hose? Is there a guide on here for replacing the foam on the heater flaps?
Well, I picked up a spare heater box thingy so I know exactly what your talking about now.. I think It'll be a dash out jobbie and remove the entire thing to do a proper job.. Btw... Is the the tape you were talking about: http://www.screwfix.com/prods/50629/Sealants-Adhesives/Tapes/Building-Tape/No-Nonsense-Aluminium-Foil-Tape-Silver-72mm-x-45m Watch this space.. i'll take some photo's and pop it up.
Thats exactly the stuff and I got it from screwfix too. It is a pain if you're applying it in situ as you have to wrap it round the flaps and as you try to apply it it just sticks to itself. If you've got a new heater box then it's dash out so shouldn't be a problem.
Right... Got this fixed now and my heater is fully working! Yay.. In fact it's so bloody hot I have to turn it off now Turned out to be a mixture of issues.. 1st - The heater bypass valves didn't work.. I tried 3 different sets and all were causing issues stopping the heat transferring to the matrix correctly. They were also causing pressure build up within my heater matrix. When I left the expansion tank cap off and rev'd the car, the coolant would surge out of the tank! I just removed the bypass valves and replaced with some 22mm copper joints from B&Q for about 3. 2nd - My heater matric was ever so slightly blocked! it was only 3 months old too.. I removed the matrix, shoved a bare hose pipe into one end and just let the water flow until clear.. I also did this trick with the rest of the coolant system and radiator. 3rd - The main culprit. The heater box which controls the air flow distribution has metal flaps inside which direct the airflow. Now, these flaps are flat pieces of metal with huge holes in (I assume to save weight and cost). These flaps are covered in a sticky backed foam, which after 20 years or so of heat just disintegrate thus meaning that the airflow can't actually reach the matrix to get warm as it just goes through the holes instead. I removed the flaps, covered them in sticky aluminium foil and foam trim to aid the seals. Before: During: After: I'll do a guide in due course. On that note, I have a spare unit I bought which I am currently repairing as above. If anyone wants it for cost let me know. Just want to say thanks to everyone in this thread for pointing me in the right direct!
