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A heater core is a small radiator (matrix) that transfers heat from the engine-cooling system to your car's air heating/ventilation system. The heater core is much smaller than the engine-cooling radiator in front of the engine. This instructable will show you how to replace a faulty heater core in a Volvo 850.
First diagnose the problem: is the heater core the prime suspect?
Some symptoms of a heater core leak are:
* you are losing coolant when the heater is used.
* you are NOT losing coolant when the heater is NOT used.
* you can smell antifreeze when the heating is on.
* you can see condensed vapour exiting vents when the heating is on.
* your car's footwell carpet is wet.
* windows steam up with soapy-looking film.
Heater core failure can be a major problem because of access difficulties. If your car is a Volvo 850 then the job is not too hard, but I wouldn't recommend trying this instructable unless your car has almost all of the above symptoms (heater core might not be the cause), are a reasonably competent DIY mechanic, and enjoy the challenge of working in inaccessible and unpleasant places to save yourself a large garage bill.
The job might take you approx 4 hours of solid work, largely depending on how much antifreeze leaks out and how much you care about cleaning it off the carpet), and it will be messy.
This Instructable illustrates the repair in a right-hand-drive Volvo 850 1994 GLT 2.5 AUTO. If your Volvo 850 is left hand drive then procedure is similar but you'll be removing the heater core radiator from right hand side instead of left. In either case: you'll be removing heater core from passenger side footwell, which gives you better access than driver side footwell.
All loose removable carpets should be taken out at first sign of coolant leaking onto them, and replaced by absorbent rags or newspaper.
You'll need:
* torx screwdrivers (several sizes) and philips screwdriver.
* rags
* dry newspapers
* plastic sheeting/bags
* carpet cleaning kit e.g. wet vacuum cleaner.
If the heater core does need replacing you will also need a new heater core:
* Volvo 9144221 Heater Core/matrix/radiator. An OEM (non-Volvo) part costs circa US$150 or £100).
* two o-rings (3545586S) for installing matrix - you can probably re-use the ones that are already there, but maybe be a good idea to replace whilst you have access.
I replaced my heater core after seeing info at volvospeed.com - you might want to view that page too.
There's more info about Volvo 850 A/c & heating system at volvoclub.org.uk, but I wouldn't use hose clamps on the water pipes to core, because in my car they appear to be solid! So try to stop the pipes at outlet rather than by clamping.
Good luck!
First diagnose the problem: is the heater core the prime suspect?
Some symptoms of a heater core leak are:
* you are losing coolant when the heater is used.
* you are NOT losing coolant when the heater is NOT used.
* you can smell antifreeze when the heating is on.
* you can see condensed vapour exiting vents when the heating is on.
* your car's footwell carpet is wet.
* windows steam up with soapy-looking film.
Heater core failure can be a major problem because of access difficulties. If your car is a Volvo 850 then the job is not too hard, but I wouldn't recommend trying this instructable unless your car has almost all of the above symptoms (heater core might not be the cause), are a reasonably competent DIY mechanic, and enjoy the challenge of working in inaccessible and unpleasant places to save yourself a large garage bill.
The job might take you approx 4 hours of solid work, largely depending on how much antifreeze leaks out and how much you care about cleaning it off the carpet), and it will be messy.
This Instructable illustrates the repair in a right-hand-drive Volvo 850 1994 GLT 2.5 AUTO. If your Volvo 850 is left hand drive then procedure is similar but you'll be removing the heater core radiator from right hand side instead of left. In either case: you'll be removing heater core from passenger side footwell, which gives you better access than driver side footwell.
All loose removable carpets should be taken out at first sign of coolant leaking onto them, and replaced by absorbent rags or newspaper.
You'll need:
* torx screwdrivers (several sizes) and philips screwdriver.
* rags
* dry newspapers
* plastic sheeting/bags
* carpet cleaning kit e.g. wet vacuum cleaner.
If the heater core does need replacing you will also need a new heater core:
* Volvo 9144221 Heater Core/matrix/radiator. An OEM (non-Volvo) part costs circa US$150 or £100).
* two o-rings (3545586S) for installing matrix - you can probably re-use the ones that are already there, but maybe be a good idea to replace whilst you have access.
I replaced my heater core after seeing info at volvospeed.com - you might want to view that page too.
There's more info about Volvo 850 A/c & heating system at volvoclub.org.uk, but I wouldn't use hose clamps on the water pipes to core, because in my car they appear to be solid! So try to stop the pipes at outlet rather than by clamping.
Good luck!
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Signing UpStep 1Passenger-side footwell access to heater core case.
* Engine should be off and not hot.
* Disconnect battery.
* remove panel under passenger dash. Keep those screws in centre console tray.
* Peel down carpet carefully.
* Unscrew and gently remove black plastic panel to get access to white heater ducting.
* Disconnect battery.
* remove panel under passenger dash. Keep those screws in centre console tray.
* Peel down carpet carefully.
* Unscrew and gently remove black plastic panel to get access to white heater ducting.
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It certainly helped give me confidence to tackle the job. Was able to do it in an hour, knowing exactly what to look for at each step thanks to this. So, many thanks!
specially because you point out the screw that i was missing, the one inbetween the 2 pipes!!!! thanks so much
just one question:
lets imagine that i have no core replacement for a while and mine is broken with a big hole in the bottom (it exploded while cruising at the higway, with a huge steam flood, scary) but i am in the road and need to continue...
can i just bypass the core with a piece of hose connecting the 2 pipes?
i will loose heating but i will keep the coolant in his place (da engine), right?
will it interfere with any other thing?
good job
Dom
:O
Oh well it needed work anyway cause it rattles a lot, and the stereo was hooked up wrong. And i learned a lot about how all that mysterious stuff works back there.
Anyway many thanks, and i'll pay it forward next time i fix something i know how to fix i'll be sure to document and Instructable it.
Thank You VOLVO FOR LIFE!