I have an '88 and I removed the hot air system completely - and I live in Canada. No problems with cold start, warm-up, or driveability. I think you can remove it with some confidence. Volvo even put hot air systems on the early 740 Turbos, which of course then passed the heated air through the intercooler. DUH. By 1990 they stopped installing hot air systems on Turbos. That is enough evidence for me.
I even took the preheat system out of my 82 240 GLT with K-jet (no frequency valve) and that one runs fine too, although there is a brief period during warm-up when it is a bit cold-blooded.

You're in South Cal, right? I'd pull the preheater ductwork out and see if this solves the problem.

Also inspect your wiring harness. Do you have a "newer" version? Look for a blue and white tag on the harness near the computer connector. It will have a part number listed on it in black and check this against Dave Barton's website.
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'87 Blue 245, NA 214K

Brian, you must inspect the plastic door and hinge mechanism that is part of the thermostat set-up. I have seen many doors that do not close all the way when it's hot outside and everything is up to temp. On those customers cars we simply disconnect the "Pre-heat" tubing from the bottom of the Air cleaner box for the summer cycle. Then re-connect it when Winter is back. Or of course, find a used one that works good, an replace it. hth Tom

Hello,

No cliff shoving required. I have heard from several bricksters that the rebuilt units are prone to short life/malfunctions. I picked up a good used unit from the scrap yard last fall for 50 bucks. 90 day warranty and no problems. I would also count wiriing harness issues as a possible.

Happy Bricking!!!

Richard

87 245 DL 351,000 km
82 242 GLT 121,000 km

http://members.cardomain.com/richink