Volvo Maintenance Hints for 7xx/9xx - Bill Garland's Nuclear ...

Volvo 700/900 Heater Core Replacement FAQ Home
Volvo Maintenance FAQ for 7xx/9xx/90 Cars Version 7.5
Heater Core Replacement. [Procedure by Dave Stevens] It's absolutely no fun driving on a cold, rainy day with a couple of
inches of slush on the road, the windows fogged up, the heater off, a rag in one hand, the windows half down, and a pool of antifreeze
building up on the passenger floor tray. If you have a fluid leak in the cabin area that means the heater core has failed as
there are no hoses (those nipples you see sticking out through the firewall are part of the heater core). Presumably you've either
just had a rad flush or you've been ignoring your rad fluid change for too long (or both, in my case). Most good anti-freeze fluids
will have a certain degree of leak stoppage ability so if you've just changed fluids and it's only weeping it may "heal over", but
don't get your hopes up. Although they might work well for a case like yours, I would be *very* hesitant to use any of the
aftermarket stop-leak treatments (Bars being one of the more infamous). You might run the risk of plugging up or at least
restricting your heater core or rad. Note that these magical fluids work when exposed to air and there can easily be pockets of
air at the top of the cores. Perhaps others will differ on this, but the decision is yours.
As for dealing with this, it's going to be a tedious job and it sure wouldn't hurt to have Harry Potter -The Sorcerer's Illustrated
Guide to Volvo Heater Replacement (aka. the Volvo green Heater Manual). A quick look at my Haynes manual (the 740 '82-'88
edition will do fine) revealed some of the basic steps and invaluable diagrams. Also, a quick look in my AllData CD gave only a
few additional cryptic steps for replacement (very poor content on this as AllData is really only good for powertrain topics). If you
don't go for the Volvo manual then at least get your hands on a Haynes (try your local library) and checkout chapters 2 (secs 21-
23), 11 (secs 33-37) and 12 (secs 33, 35). Note that Haynes tells you to discharge the air conditioning system, which is NOT
required.
Here are the guidelines I've developed so far:
1. You're going to be working primarily from the left footwell (orient vehicle for good access and lighting)
2. Prepare yourself: Verify sufficient inventory of favourite brew. Brush up on four letter word vocabulary. Make reassembly
easier by using masking tape to label each screw, bolt, plastic retainer etc with a number to indicate order of removal.
This assists reassembly.
3. Loosen rad expansion tank cap then clamp off heater hoses and disconnect at firewall (old hoses can be a real pain to get
off; nipples are delicate; be prepared to catch fluid when you succeed). To be able to drive the car without the heater,
simply join the two hoses (a 1/2" i.d. copper pipe 90 deg coupler works well)
4. Disconnect battery as a precaution when working around dash accessories and the relay tray.
5. Remove ashtray (and holder), lighter (pull lighter plastic bezel straight out) and storage box (remove two screws and
swing out at left).
6. Remove shifter console: Two screws under plastic clip in bottom of storage box. Remove plastic cover below brake
handle and pry off metal clip at front of console (under ashtray area) to allow centre section of console to be spread and
moved around shifter column. Disconnect seat heater switches and swing entire centre console back up out of the way.
7. Remove left under dash panel: Note Torx head screws. Disconnect and remove air duct under steering column.
8. Remove right under dash panel: Carefully work plastic covering around heater fan motor.
9. Remove glove box: Note two nuts on either side.
10. Remove radio: Flat retaining clips hold side edges. Remove knobs (pull/pry straight out). Clips should be visible behind
outer edges. Insert hooked wire through knob openings (upward and outward). Grab clip and pull in slightly to release clip
as you work console out. Remove radio compartment (held by screw in tab at upper rear).
11. Remove left and right console side panels: Remove side panel bolts (1 at lower front behind carpet, 2 at lower rear behind
carpet, 2 at upper front inside console at radio slot area). Detach lower crossbar (pull both panels forward slightly to allow
screwdriver access from rear; loosen screws; bar is slotted on both ends).
12. Remove heater control panel: Remove surround trim (carefully snap out trim with protected blade gently prying inward
and outward; note the metal retaining clip holding the middle of the trim panel to the right of the electrical switches -
release clip from behind dash by pushing toward switch; disconnect switches). Remove metal bracket below heater
controls. Remove heater control panel and swing out of the way to the right.
13. Remove ducting: Remove right and left outside face vent ducts (behind glove box and behing instrument cluster over
steering column). Remove centre panel vents (remove short duct then push out vents). Disconnect floor vent ducts (peel
back carpet; remove tunnel duct screw; reef out plastic stud; pull back rear floor vent ducting and wiggle off floor
distribution box outlets. Remove floor distribution box from under main distrbution box (release relay tray and swing out of
the way to the left; remove relay tray frame; remove centre screw securing floor distribution box to main distribution box;
remove floor distribution box sliding out to right side). Remove main defroster duct to allow access to upper distribution
box cover screws (unfortunately this duct is secured with grip clips on plastic studs that will seemingly break off during any
attempt at removal; in order to gain restricted access to the upper distribution box screws you can try just removing the
foam collar from the base of the duct and working through that restricted gap).
14. Remove air distribution box cover: Remove the *12* screws securing the distribution box cover (including two in middle of