68 Toronado intermittent heat

[Dayton]

Fellow Toronado owners, I need some help with my 68. When I first start the car I get heat idling and even driving at 10mph down my mile long lane. The heat level is very hot coming out of the vents.....until it stops working. About a mile into highway speed, heat drops off and does not come back until I let it cool down and start it up again. By cool, I mean almost stone cold. If switch the temp bar from hot to cold there is minor difference in air temp...this after heat stops. After heat stops the temp when on hot is ever so slight warmer that when on cold but definitely not enough to stay warm here in Illinois, lol.

Some background information:
--It is the manual heat/ac control.
--Car has 43k miles.
--Coolant system is full and burped for air.
--Coolant system has been flushed. Flush
revealed some thin brown sludge...normal
amount from a flush. No sign of sealers
having been used.
--Radiator fluid is 50/50 mix.
--Vacuum lines are all soft and smoke checked.
No leaks.
--New thermostat, checked old one and it
worked fine. Both are 195 degree.
--4 season valve is new.
--Both hoses are hot going to heater core.
--I have checked all vacuum connections, as
well as the smoke check.
--I disconnected the heater core hoses and
blew air through it....air moved freely and very
little dirty brown came out towards the end. I
ran air till nothing came out except air.
--All vent choices work on the climate control.
--AC is charged and works fine.
--No kinks in hoses and all coolant hoses are
new.
-- No signs of a coolant leak anywhere, no
overheating and odd noises from anywhere
under hood or inside the car.

Since 1985, I have owned several 69 to 70 Oldsmobile Delta 88s and a 98. I have never encountered this problem before and I do not know what else to check. The fan motor works fine, however it blows at only high speed, it's either on or off, no adjustment. I doubt this is a factor in the heat issue.

Have any of you encountered this problem? Do you have suggestions as to what else to check? Any help is greatly appreciated.

[Ourkid2000]

Although I'm no expert, that certainly sounds like your heater control valve is acting up. I know you said yours is new but some of the experienced fellows I've spoken with tell me these new valves are often troublesome. There is a version of that valve available that can be physically manually closed or opened rather than by vacuum signal. It would be easy enough to throw one of those in there and set it to the open position and see how your heat behaves.

Or you could just cobble some kind of bypass together with pipe fittings that would do the same thing.

[Otto Skorzeny]

Yes, it sounds to me like your heater control valve is malfunctioning. There are several companies that rebuild those valves. I believe the Toronado one is a Ranco valve but it might be Harrison.

Here are a couple companies that rebuild these and actually have new ones in stock.

Joe Hudacek Rebuilder of Ranco and RobertShaw heater valves. New Ranco heater valves for sale
6606 Banks Avenue
Superior, Wisconsin 54880
715-392-6169
Cell: 218-213-8906
http://www.heatervalves.net/


Jim Tucker Rebuilder of Harrison and Ranco heater control valves. New valves for sale 1950 -1975
29597 Paso Robles Road
Valley Center, California 92082
760-749-3488
http://www.heatercontrolvalve.com/

[Dayton]

Thanks guys. I will get another valve and see about a rebuild on the old valve.......although I am not sure whether that old valve is the original. I kept it just in case it was.

As to a manual valve....I had never heard of one being sold anywhere. Building one wouldn't be too hard.

Today or tomorrow, depending on time i have, I am going to unhook the heater core hoses and flush the heater core separately using vinegar. I have used vinegar for many types of cleaning....works well. Then see what happens when I hook it back up. If doesn't work, move on to valves.

I am wondering, after reading through the service manual, about the possibility of doors in the heater core area not working correctly. Is it possible one of those is operating incorrectly? If so, what diagnostic steps do I take to start checking those? (Assuming that may be the problem)

[Dayton]

Searching, I found manual valves. I am surprised I never heard of these, though I had never looked. I am going to order one.....it will be a great tool for diagnostic purposes.

[Dayton]

Update: problem of no heat seams to be the AC & HEATER CONTROL in the dash. The vacuum is no holding for the dash hvac control, which is a manual one, not the comfortron.

Does anyone have one for sale or know of a company who rebuilds these ac/heat dash controls? It's for a 1968 Oldsmobile Toronado.

[Ourkid2000]

Are you 100% on that being the problem? Those controllers have a vacuum selector valve that is basically machined to be tight. There's really nothing to go wrong unless it was underwater for some time. I'd be surprised if yours isn't still good.

I removed mine on my '66 (manual AC) and just cleaned bewteen the two mating surfaces of the selector valve and re-greased it with some Superlube grease. It's definitely not ever going to be a perfect seal and will probably always leak a little but it works just fine.

Leaks in this system are almost always gonna be the usual culprits.......hoses, etc. Everything is hooked up to the correct ports on he valve right?

[Dayton]

From the entire thread you can see all the things I checked or replaced, except the following I just had done: replaced water pump, had entire radiator system flushed again with a pressure check, replaced radiator cap, replaced 4 season valve again, had my shop check all vacuum lines (using a vacuum gage). The vacuum line from the 4 season valve, when checked driving, is losing vacuum once to highway speed. That line runs directly to the control unit. I and my shop checked the lines color codes to insure proper position on the control unit per the manual.

It's the dash controller, imo. If it isn't, what else is left to check or replace? The only line dropping vacuum is going to the controller from the four season valve. BTW, that line was separately checked for leaks with none found on the hose.

I can't seem to find one, am not sure what years inter change, nor can I find a rebuild company.

Does anyone have information on buying a AC & HEATER CONTROL for a 1968 TORONADO?

I looked for NOS and didn't find one, either.