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

Yeah - get back down there by the HCV and feel the hoses going to/from the core. With the engine at full temp, HCV wide open, blower fan running at 3 or 4 and the controls set to put outside cold air through the heater, both hoses should be hot. If the return (lower hose through the firewall) is significantly cooler than the other, you have restricted coolant flow. Rev the engine to 2000 or so - little or no change?..pretty much confirms it. Can probably eliminate the new HCV as the cause so I'd bet on a (partially) plugged core. My cure for that is at- http://www.brickboard.com/RWD/index.htm?id=738840

Also sounds like you have some problems with the vacuum operated valving on the heater/defroster ducts. They should blow the same temperature (left and right). Or....(Horrors!) one of the blower's squirrel cage fans has come loose on the motor shaft on one side and isn't putting out. Is the air volume (not just temp) weak on one side?
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Bob (81-244GL B21F, 83-244DL B23F, 94-944 B230FD plus grocery-getter Dodge minivan, MGB, and numerous old motorcycles)

Hello Bob, and thanks for your and all's informative replies. I read y'all's volvo words of wisdom all the time.

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'

Bob
CLR sounds like a good idea but why not use it to flush the cooling system?
Thanks Dan
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85 245 M46 190K, 92 245 A70 117K

I didn't like the idea of a strong chemical contacting the entire cooling system, unless it's specifically designed for automotive purposes - and those are out there.

CLR seems to be fairly potent stuff, and its makers aim it at coffee makers, tea kettles, cleaning up the scale and staining in porcelain fixtures, etc. I didn't feel comfortable with it circulating inside the (replacement cost) $150 radiator, $400 aluminum cylinder head, and so on. It might be perfectly OK, but by isolating and treating the (small volume) heater core I could use it 100% full strength, and observe and control the process.
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Bob (81-244GL B21F, 83-244DL B23F, 94-944 B230FD plus grocery-getter Dodge minivan, MGB, and numerous old motorcycles)