Hi Folks!

It was 8 degrees this morning and now it has warmed to a balmy 15 degrees. I don't seem to be getting any heat in the cabin of the car. Living in tropical Minnesota this is a real problem. I am not sure whether the vent wheels need to have the white side out of the black side. I have tried both and it doesn't seem to make a difference either way. The butt warmer on my side works, but the passenger side doesn't.

Given my medical problems this is really big thing. I have a big sensitivity to cold in my hands and feet. The diabetes is a real problem and I also have Raynauds' Syndrome.

When I drive to work, I can see my breath. The fan works just fine.

Anyone have any any ideas? I have never had this type of problem in any of my Volvos, and I have a plethora of them: a 544, 122, 164, 240, and one whose number I can't remember (pre 240)

Any ideas?

You have a control valve up against the firewall in engine compartment directly behind motor. it is attached inline on a nose that goes to you heater core. It could be malfunctioning and not letting hot antifreeze get to your heater core. It is mechanically activated via the slide thermostat on your heater/ac temperature control in your car.

JMSH

I refilled the overflow the other day, but it only lasted me about 5 days, so something is leaking. I can smell coolant in the cabin. On Saturday it was -7 degrees and my hood was frozen in place. I went to a local gas station and got help getting the hood open. I have been carrying some anti-freeze in my trunk to fill the overflow; despite the danger of getting scalded when Islowly open the overflow. I still don't know what the problem is. I can't deal with the cold, no matter how much I am bundled up.

If it is the heater core, are they available used? Does anyone have one? It is a little warmer today, so I will take the car to a mechanic. Hate to do that, because I could figure out that is wrong if the weather was more temperate.

Sound like it is in fact the heater core. Check the carpet and underneath on the passenger floorbaord for coolant. If there is coolant there, it must be the heater core.

As for buying a used one, you could probably get one from a junkyard, but there are no guarantees, and the job is so timeconsuming i don't think it worth the risk. I would buy a new one, i just got mine from fcpgroton.com.

As i said the heater core is ver time consuming to replace. Everything under the instrument cluster and the glove box (including the glove box) must be removed to get to it. There is a write-up on faq that goes through the steps. It is up to you whether you want to do it or not, but i know it is expensive if you have it done at a shop.

Coolant is toxic though, not good to be breathing in everyday. The sooner you fix it the better.

Good Luck -

Brant

I refilled the overflow the other day, but it only lasted me about 5 days, so something is leaking. I can smell coolant in the cabin. On Saturday it was -7 degrees and my hood was frozen in place. I went to a local gas station and got help getting the hood open. I have been carrying some anti-freeze in my trunk to fill the overflow; despite the danger of getting scalded when Islowly open the overflow. I still don't know what the problem is. I can't deal with the cold, no matter how much I am bundled up.

If it is the heater core, are they available used? Does anyone have one? It is a little warmer today, so I will take the car to a mechanic. Hate to do that, because I could figure out that is wrong if the weather was more temperate.

Find the two hoses that go to the heater core at the firewall. With the engine warmed up make sure that both tubes are hot. If if one is hot and the other is not, you have an obstruction in the heater core. I was able to clear up a blocked heater core by reverse flushing the core with a garden hose.
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Paul NW Indiana '89 740 Turbo 128,000

The air vents are on when the white stripe is showing, but only if the air distribution knob is in certain positions. The air coming out will be cold if the heater is not working.

The heater controls on the 740 are vacuum operated. You should be able to hear hissing noises and the opening and shutting of flaps under the dash as you move the air distribution knob to different positions with the engine running, or right after you have shut it off. The heater control mechanism is somewhat fragile on these cars, but is not too hard to replace, if you can find a good one.

The heater valve is also vacuum operated. It is under the hood, next to the firewall, just to the left (car's left) or drivers side of the engine. It could be as simple as the vacuum hose that activates it having split and/or fallen off.

Is the engine warming up properly? It is not unusual for the thermostat to fail in such a way that it is stuck partially open. When this happens, and it is cold out, the engine never warms up. Result--poor gas mileage and NO HEAT! I've seen it several times, and a new thermostat can make a huge difference.

According to the temperature gauge it is. Would the broken hose be easily visible?

Assuming the temp gauge is correct, and the engine is indeed warming up (the gauges in later cars, 240 and 740, don't read the actual temperature, they just go to the middle and stay there unless the car overheats) the heater valve is the next thing to check. The hose I was talking about is a small vacuum hose, about 1/4" in diameter. It should be connected to an even smaller metal tube (1/8", maybe) on the side of a round capsule about 1 1/2" in diameter that is part of the heater valve. The heater valve also has two large water hoses (1" outside diameter) connected to it. If the small hose is connected properly, there are two other likely possibilities: No vacuum (usually a problem with the heater controls in the dash) or the heater valve itself has gone bad (which it can do without causing a coolant leak--it just doesn't open any more) You will need a helper for part of this next test. Find the heater valve. Check the vacuum hose. If it's OK, start the engine and have your helper watch the heater valve while you move the heat control knob back and forth. You should be able to see movement of a small lever arm on the side of the vacuum capsule. If no movement, pull the small hose off and see if there is vacuum, which should vary as the knob is moved. If there is vacuum, try to move the arm on the valve by hand. It may feel springy, but it should move somewhat. If it is completely jammed, you need a new heater valve.(a further check of the heater valve is to run the engine for a while, with the heater on full, then feel the two large water hoses that go to the valve. They should both be hot. If they are both cold, or one is somewhat warm, the heater valve is not opening. If both are slightly warm, but not hot, it is time to take a closer look at the thermostat.) If the lever arm moves, you may be able to temporarily tie or wedge it in the open position, so that you can have heat while you troubleshoot the vacuum problem. Be careful not to damage anything if you try this. You don't really want to leave it like this, as the heat will be on all the time which makes the car slow to warm up. I have found on mine (with everything working properly) that it warms up A LOT quicker if I leave the heater off until the gauge gets at least half way up to the normal position before I turn on the heat, which is usually only a couple miles. I can then turn on the heat and warmth actually comes out the vents. If I start the car with the heater on, it takes at least twice as long to feel anything, because the engine has to heat both the water in the engine and in the heater at once. With the heater off, only the water in the engine has to be heated, which happens quickly, then you turn the heater on, and hot water goes to the heater, and the cold water that was in it goes to the warm engine and is rapidly warmed. All of this takes place before the whole system is up to operating temperature, at which point the thermostat should open.

Did the no-heat situation happen suddenly, or was it a gradual thing?

I haven't had to use it (the heater) until now.

Thank you for all the input. I am going to check the coolant, and try running it until the engine warms up and then turn the fan on. Sadly, I don't have a garage I can work in. My house is over 100 years old, and I have a two story barn/garage with room a horse or a Model T, but no room for a modern automobile.

If you wind up changing out your heater control valve, change the hoses also if original. fcpgroton.com has pretty decent prices.
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Post Back. That's whats makes this forum work.

I can't deal with this alone and without a heated garage. I might be able to add coolant, and I just got home from work, so it is took late to ask the 8 to 5 'ers.

I hate to pay someone at a garage to check out that hose, but I think I will have to.

Where are you in Minnesota? I just did the heater core and heater control valve on my 740. I live about an hour east of the twin cities at UW-Stout in menominee. May be there over the weekend.

Well, I DID discover that the coolant was way down. I filled her up to the top of the overflow tank, and that did the trick.

I know I have a leak someplace, obviously from the coolant level being low. I couple of months ago I had to add stopleak into the traes in mnny because it was leaking like a sieve, so I always check the place where it is parked now.

The odd thing was i haven't seen any coolant on the ground, although I get a whiff of coolant when I run the heater, so there is a leak somewhere. I will just have to be careful and monitor it more closely. A bottle of antifreeze now lives in my trunk alomg with some oil and tranny fluid.

"Ugly Betty" has new tires and brand new rear breaks, and she is a winter car. I wouldn't mind finding an afforable 740. I have gotten to like the little luxuries. Remember, my other car is a "67 122 wagon, so even a bashed in 740 with a coathanger sticking out where the antenna used to be, with the headliner coming down is a luxury to me!

Sounds like the heater core may be leaking. Check for fluid on the passenger floorboard. If your heater core is leaking, it will be there. The other thing, you may get some very foggy windows if that is the case.

The fumes of antifreeze are toxic. You do not want to breathe them. If you can smell it coming out of the vents, when the heater is on, it is likely to be the heater core. Bad news---that's a big job. If the leak is major, you will indeed find a pool on the passenger side floorboard. It is also possible that the leak is coming from a hose under the hood, a hole in the radiator, a bad cap on the reservoir, that doesn't hold pressure, or maybe even the water pump. If that was the case, you would smell hot coolant when the car was warmed up, whether the heater was on or not. If it's the heater core, you can try putting a stop-leak product in, but in my experience, that stuff rarely works, and it can clog up the radiator, so I don't recommend it.

A few years ago I had an old diesel Mercedes. The main reason I got rid of it was because the heater core leaked. Not enough to make the level go down in the bottle under the hood, but just enough to smell. I had already replaced it once, and was not about to do it again. After suffering through a typical winter in Northern Virginia (we call it cold, and it sometimes snows, but it's nothing like you get) with no heat (it actually worked, but I would not use it) I sold it cheap and bought a 740, which I fixed up, and still have.

If you want to replace your current winter wagon, what you need is to somehow get a car from down here. Good solid 740s, with no rust or major mechanical problems, are not hard to find for less than $1000, sometimes quite a bit less. If you know anyone going to the DC area, maybe they could fly down and buy one and drive it back.

Would pictures of the parts involved be of any help?

You don't have a handy friend who is a little more mechanically inclined, who could come look at it for you? I would offer to do so, but I live in Virginia, about 1000 miles away from you.

You know, just knowing there are people out there who would be willing to help if they weren't so far away, gives me the gumption to stand out there in single digit weather and soldier on.

Thank you all! The body of the car has so much damage I only put in the neccesities in her. The motor has only 168,000 miles on it.

Nice to speak on this forum. Thank You so much!

I just happened to see this. Hi Cynthia! That old wreck is still running? Good thing you figured out the heat problem, single digits are a problem around here.

I wasn't around for turkey day, but call me or send me an email if you have other problems. My garage is a balmy 38F and there is a little space to work on your 740 when you need it. I have a Chilton's for reference.

You know me, nothing to do all day!

Klaus
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The 164 has a new home, all I am left with are a 95 854T and a 98 V70R :)

He has enough to do with 2 small kids, maintaining this site, working for a living and spending time with his wife.

How much does a heater control valve generally cost?

http://www.fcpgroton.com/volvo700900heating.htm#heater
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Post Back. That's whats makes this forum work.

Check that the coolant is topped up. Also check the heater controller is working in the engine bay near the firewall. Good pluck

It is supposed to be 26 degrees today. I haven't checked the coolant lately. It would be great if I only needed to top off the coolant. Just bought new tires and had the rear brakes done, (I am not a DIY) and it sucked out the little I have saved from my disability check over the last few months.

C. A. I'm sorry to hear that, I belive that your fault lies in the control valve, which may not be letting coolant flow into your heater core. check this out http://www.volvoclub.org.uk/faq/HeatingAirConditioning.html#HeaterProblems

C. A. I'm sorry to hear that, I belive that your fault lies in the control valve, which may not be letting coolant flow into your heater core. check this out http://www.volvoclub.org.uk/faq/HeatingAirConditioning.html#HeaterProblems