86 Volvo 740 Turbo NO HEAT =:0(~

Once the beast warms up, check the temperature of the return line heater hose (runs from the heater core back to the engine) to see if it's warm/hot.

If so, no obstruction in heater control valve or core.

Hey, Thank you... And if the return line is not hot? How can I tell if the heater valve is working? If I push the lever thingy, it pushes in. Thank you David

Hi there, OK, I went and ran the car. The Valve is on the lower hose. The hose before and after the valve is hot. The hose coming off the top is not warm at all. Im guessing the valve is ok?!?! The heater core is blocked? If so how do I get it unblocked? Will flushing the whole system make it better? Is there a way to flush the heater core by itself, with out removing it? Thank you David

I can only speak about the vehicle I have done this on, a 1981 244, but assuming the layout is similar...

Remove the panel to allow acces to the heater control valve (on the

244, it's above the gas pedal, slightly to the right, near the firewall).

Move the temperature control handle while watching the movement of the heater control valve; if it feels normal, with slight resistance, the valve is probably OK, and the problem would lie with the heater core, which is "downstream."

To confirm: feel the temperature of the hose leading from the heater control valve to the heater core, to see if it is warm/hot after car is warmed up.

If it is cold, and the temperature control handle is in the full open / hot position, the heater control valve needs to be replaced.

Otherwise, the core is toast (obstructed).

Of the two scenarios, the heater control valve is the more likely culprit.

Sorry Im confused. The two hoses that go through the fire wall do not go directly to the heater core? What is the Heater control Valve? Is that the one that is in the engine compartment on the 740, on the bottom line going in to the heater core? If so that is hot both before and after. If it is the core, can it be flushed while still installed? I hope its the heater control valve, but Im thinking its not.

Pull the control panel out and check the white vacuum line to make sure it is not pinched or crimped. Check the vacuum lines just to the right of the gas pedal for the same thing. Usually the vacuum supply pipe gets crimped and there is no vacuum to the heater control valve.

Bob

Easiest way is to remove the valve and run water through it, pushing the lever should open or close the flap.

Sometimes these old valves get fragile though, some are plastic and I broke the pipe off of one, but then if that happens it was ready to go anyway.

700 series is completely different, the heater valve is vacuum operated and is located in the engine compartment.

Thanks, good thing I qualified it.

Still, the troubleshooting methodology might transfer over.

Awesome...Thank you all.. Ill try those things today and see. Hopefully its vacuum line or the valve, hate to think its the hater (Ha ha) core. (Heater core). Will let you know...

snipped-for-privacy@comcast.net wrote:

OK I did some trouble shooting. I think it vacuum, BUT the cable to the dash control is broken in the plastic wher it screws on. So I ordered one from Volvo. Gonna be a hard change but worth it if it fixes this. I also found this on line as well.

let everyone knwo what happends.David

OK I did some trupble shooting. I think it vacuum, BUT the cable to the dash control is broken in the plastic wher it screws on. So I ordered one from Volvo. Gonna be a hard change but worth it if it fixes this. I also found this on line as well.

let everyone knwo what happends.David

Are there any 740s in USA/Canada that do not have air conditioning, or is it a universal thing?

All the best, Peter.

700/900/90 Register Keeper, Volvo Owners Club (UK).

Will let everyone knwo what happends.> David>

I'd be shocked if the heater core were the problem, that'd have to be one heck of a clog!

My guess is a vacuum line cracked, haven't had that happen on the heater valve but I've had plenty of other vacuum lines do that, some of the ones in the '88 Saab literally snapped in half when I pushed them out of the way. They'd turned completely hard and brittle.

It's universal, all 700 and 900 series cars came with A/C, EFI, power windows and heated seats. Every one I've ever seen had a sunroof too, though I've heard rumors that some came without.

Volvo has the opposite problem. THe tubing is so soft it collapses and kinks when the weather is hot and takes a set in the collapsed form when the weather gets cold. Sometimes there's enough cold from the A/C to set the hose in the summer and then none of the inside vents work either.

Bob

In Canada, all 85 740s came without A/C, but all had the A/C adaptable heating system. Most had A/C installed at the dealer level. In

1989/1990, some of the cheaper models (740 with no letters) came without A/C (and cheaper interiors and steel wheels) to try and get their list price down. The price of the dealer installed A/C was so ridiculously high that they ended up having promotions to give A/C away as very few people paying "Volvo money" were interested in a car without A/C. (These down contented cars also came without a sunroof.)

Interesting, yet another case I was unfamiliar with of strange versions available in Canada.

For the US though my previous statement still applies, if there were any exceptions, they're extremely rare.

OK so the dealer called and said the cable is back ordered. does anyone know where I can find a cable after market maybe? ITs 65.00 thought the dealer... OUCH... Hope this fixes it... I did find that one vacuum leak out by the water valve, heater valve, what ever they call it right now. Only think is, I need to find the solid line, the soft vacuum line wont hold up once its warm out. Any ideas?

Thanks guys, David