Dream Whip

I have a '75 Ninety Eight Regency. It has one heckuva heater.

Which is nice, except, it doesn't want to do anything but give maximum heat.

The car has standard (not temp specific) climate control. And I can change the mode fine--for example, if I switch to defrost, the maximum heat will come out and defog the windows in about 2 seconds, and if I put it on a/c, the compressor will turn on and maximum heat will be blasted out of the dash into my face.

But it's only heat. Even if I push the temp control all the way to the left.

Now if I put my hand down over to the right, under the glove box, near what I believe is the heater core (haven't received my factory service manual in the mail yet so still getting oriented), I can feel the temperature change when I adjust. But out of the ducts up top and the vent duct under the ash tray? Only heat.

I had this problem come up on a newer Cadillac I had, and it was a door actuating servo thingy that had to be taken out and replaced. But that was a 90s Cadillac with electronic climate control and a computer.

The Olds is much older, and possibly different...maybe, I hope, easier to fix (as I recall, I paid for a mechanic on the Caddy because it involved removing a fair amount of the dash and I just didn't want to deal with it).

Thoughts?

oldcutlass

Is there a water cutoff valve in the rubber hose that feeds the heater core?

MDchanic

Sounds like your temperature adjustment cable isn't hooked up.

Wait for the manual, then check out the detailed information about the A/C system - it shouldn't be hard to pinpoint.

- Eric

joe_padavano

That's irrelevant. The water valve on that car is only closed at MAX COLD on the A/C. at all other settings it's full open and has nothing to do with regulating temp. As Eric correctly points out, the problem is in the heater blend door seals or control.

oldcutlass

I thought it shuts the water flow when the heat is selected off, my mistake.

Dream Whip

Thanks, folks.

I am eagerly awaiting the manual which will hopefully diagram this decently, then I'll try to figure it out, but good to know that it's probably one of two things.

rocketraider

It is standard AC? Because that sounds like the kind of thing a Tempmatic will do.

Maybe you'll get lucky and it's just a disconnected cable. If it's broken might be fun to find a replacement. If it's a vacuum motor some major disassembly may be involved.

Dream Whip

Well, I don't have the original options sticker. But, I believe it is standard.


There are


1. No numbers on the red and blue lever guide
2. It doesn't say "Tempmatic" anywhere


http://www.oldcarbrochures.com/stati...20Pg%2030.html


It's the "Four Season" one at the bottom. No fancy script or fancy ****.

Dream Whip

I'll look at the FSM when I get it and see if that sheds any light on it. It's hard to talk about something I can't yet visualize. If it is a cable and no replacement is available, perhaps one can be "fashioned".


Either way, sounds like something I may end up leaving to someone who does this for a living, and I'll just stick to plugs, wires, brake pads, etc!

Yellowstatue

On my Eighties Regency, it was easier to remove the glove box to get better access to the temp control because you can sit upright and see what you are doing. To shut the heat off, pull the vacuum line off the manifold water valve and plug the hose.

joe_padavano

I know that this is correct for the 1977-1990 full size cars and the 1978-1988 A/G-body cars, but I do not know if it also applies to the earlier cars.

Sorry, that won't have any affect. On the OP's 1975 (actually on any 1971-newer full size and any 1973-newer A-body) the manifold heater valve is normally open and closes when vacuum is applied. Disconnecting the vacuum line will only keep the valve open (and hot water flowing) at all times. This is confusing sometimes because GM completely changed the function of these valves in the early 1970s. The early valves were normally closed and opened when vacuum was applied. The later valves are normally open and only close when the A/C is at MAX COLD.

Dream Whip

I forgot to reply to this.

1) Whoever thought it was TempMatic, an ice cream sundae for you, because I just couldn't see that the TempMatic decal with the temperature control had faded.

2) It was the cable attached to the blend door control. I found another one, and, once replaced, the a/c and heat work fine. Thank God.