I have an 86 240 wagon which i replaced the heater control valve with the plastic kind from fcp groton. with the old style hcv, i had either hot or cold. the car has a new volvo oem w/p, too. the heater hose to the hcv is hot. so no problems up to the hcv.

the new hcv is installed correctly, but now, when switched to full heat, i have fair heat on the 2 passenger side vents (better when the a/c is switched off), but cool air is coming out of the 2 driver's side vents.

i've checked the archive here and bentley's, but so far information is inconclusive. i'm pretty sure i don't have a heater core leak. the last thing i hope to hear is to replace that buried heater core. any ideas?

Thanks!!
BC Golden (bc1_2002)
86 245 230k+ mi; original owner

PLS NOTE: I forgot to mention that the fan blower is working fine.

Sounds like you already suspect the heater core. The original cores I've seen are divided in half with separate outlet pipes joined in the center. So if you feel cold air from one vent and warm air from another, at the same relative strength, this division in the core is the only plausible influence.

You didn't have that symptom before you did the replacement, so it is just likely the surgeon dislodged a chunk of plaque into the constricted arteries of the heat exchanger and your core had a "stroke".

Before doing a transplant, try confirming the diagnosis by going in through the upper radio slot or center vents (maybe arthroscopically from behind the glove box?) to feel the copper exit pipes on either side of the top of the core before they join in the center. Then arrange some configuration of garden hose and maybe heater hose and a five gallon bucket to reverse flush the core.

Actually, I just read an excellent thread on salvaging the heater core suggesting a chemical cleaning method.

I'm waiting for the snow to subside to replace a heater core, so if you're not lucky with the backflush, stay tuned for anecdotes on a core transplant.
--
Art Benstein near Baltimore

Hello Art, and thanks for your and all's informative replies. Very informative as always!!

No, the air flow is the same on each side as the other, as well as in the defrost and floor vents. I checked the heater hoses on the hcv side & passeng side going in to the heater core and they are hot.

I've checked the return heater hose in the engine compartment--it's not as hot as the intake, but it should be slightly less hot, but I'll drive it aroung to see how hot the return hose can get.

So, the original heater core is partitioned inside--fluid flows down one (right)side and up and out the other (left) to the outlet?

Byron Golden
near Houston
86 volvo 245 230+k miles and still smoothly cruisin'

>So, the original heater core is partitioned inside--fluid flows down one (right)side and up and out the other (left) to the outlet?

I think it is more like it flows to the middle and splits to either side and is collected separately before the exits join at the top. A bit hard to see in this pic, but the pipe that faces south is the exit. It joins the collector pipes from north and south at a tee in the center. The pipe that faces north disappears to the center of the core and is the inlet from your heater valve.

Art,

Thanks for the jpeg--make sense about the water flow in the h/c.

I've just completed backflushing my heater core as suggested in your link. But instead, I merely disconnected the 2 engine heater hoses from the engine compartment nipples and connected the water hoses there. So, no sore back tomorrow.

The results are significant. Much hotter air comes out of all vents. The driver's side may not be as hot as the passenger side but still a lot of heat. Good enough for freezing temps & Houston's mild winters (no snow).

It took about 30 min for the back flush and 30-45 min to gather & assemble the pieces from my garden stuff. Hopefully, should do well for a number of years, and I look forward to your msgs on bb about r/r the h/c.

Hope the team you want to win in the super bowl wins & thanks to all's important help & suggestions.

Byron Golden
Houston area
86 245 230k+mi (with heat!), (lrg tach,clk,oil tmp/press,amb temp,volt,pwr heated side mirrors all added)

check the vacuum reservooir down by the passengers feet...if a line is off the shutters wont work correctly, and wont route the air to the vents.

Ian

Hello Ian,
Thanks for your reply. As you suggested, I checked the vac hoses on each side of the white plastic reservoir and luckily or unluckily, are hooked up, but I haven't checked the vac hoses behind the console. Maybe something is loose back there, but I don't hear any unusual hissing sounds at this time.

Regards,
Byron Golden
near Houston
86 volvo 245 230k+ mi & still smooth-cruisin'