thomaswatk

Had some work done on the a/c - heat switch and when I got the car back if I push the temp lever to hot....it puts out cold air...and when pushed to cold...it gives out hot air. (The selector lever in A/C) Would rather not have to go back to where the work was done right now so can anyone tell me if its an easy fix....
Thanks

joe_padavano

Year? Model? With Comfortron or not? What work was done?

Vintage Chief

Car....what car? I'm guessing you have a 68 Cutlass S & I'm guessing it's the car w/ the buggered up AC/Heater. But, no one here has proven capable of mind reading up to this point. Many have tried, but the migraines are painful.

toymobile

Without the right info I would guess that the wrong heater control valve was installed.

Good luck Johnny

thomaswatk

Well, when I mess up, I do a good job of it.........It is a '68 Cutlass S with the original heat/ac. When I took it in to have the fan switch replaced, I was told it needed two other switches which I bought, and they said they replaced them. Seemed strange since everything worked fine, except the fan switch, when I took it in to them. Anyway, now the heater and ac work, but in reverse order according to the temp lever.
Sorry for the migraines Vintage Chief, but you sure do live in a beautiful place. I don't think a headache could last long if you go outside and enjoy your surroundings.

tru-blue 442

Take it back and have them make it right.

JohnnyBs68S

If I'm not mistaken, the temp lever controls a door in the ductwork that allows air from either the AC evaporator or the heater core to flow into the cabin. Somehow it seems they got that to work backwards from what the factory intended. I'd check out that cable and its connections at both ends.

joe_padavano

You need to clarify what "heat and A/C reversed" means. Are you getting hot air on A/C and cold on heat, or does the air blow out the A/C vents in the heat setting and out the heater vents in the A/C setting. These are very different problems. As noted above, the temp is controlled by a cable on the slider. I don't think it's physically possible to reverse the function of that, at least not without a lot of work. It IS possible that the cable is adjusted incorrectly. On the other hand, if the problem is flow from the wrong vents, that is likely caused by incorrectly attached vacuum lines on the control head.

And if you told the shop to do one thing and they replaced additional items that weren't needed, they likely busted stuff when they hamfistedly removed the control head and you should not be paying for that or to fix it twice.

thomaswatk

I thought my original post clarified the problem, but I'll try again.......... With the select function lever in the ac position and the temp lever/slide in the cold position.......it puts out hot air..........when the temp lever/slide is in the hot position.........it puts out cold ac air.....Both the hot and cold air come out the ac vents. Since it's summer and still quite hot here, I'm sure the hot air I feel is actually outside air. I just want the ac air to come out when the slide is on the "cold" side. I'm not very good at explaining stuff, so I hope this is better than the other attempts.
Thanks for trying to answer in spite of my, less than stellar, attempts at explaining.

joe_padavano

What happens when the mode lever in in the HEAT position? What temp air and from which outlets? How about in DEFROST? Did the shop replace the heater control valve on the intake manifold?

thomaswatk

The heater control valve was not replaced. I had forgotten since it's summer, but there is a shut off valve in the hot water line which I use during the summer. Apparently, the control valve was letting hot water through even though the system was in the ac mode so both heat and ac were both on at the same time. When the shut off valve was installed several years ago, the problem stopped. When cold weather arrives I simply open the shut off valve and the heat operates correctly.Right now the Olds is up on the lift with a car under it, so I can't check the heat function.

joe_padavano

So this suggests that somehow the system has been mucked up for a while and someone installed this half-fast shutoff valve to bandaid the problem. Your car requires a normally closed heater control valve that opens when vacuum is applied. It's possible that yours is stuck but it's also possible that someone inadvertently installed a later valve that works the other way. If the vacuum hose had been disconnected from that incorrect valve and the shop helpfully reconnected it, that would reverse heat and cold. Again, without full knowledge of exactly the configuration of your car and preferably photos of things like that heater control valve, it's difficult to home in on the cause.

thomaswatk

I understand exactly what you're saying, however, at this time, my only question is how do I reverse the warm/cold function ? When I slide it to warm....it gives out cold ac air. When I slide it to cold it puts out warm air..........how do I reverse it ? Is it a vacuum issue or a cable issue ?

joe_padavano

And what I've been trying to tell you for the whole duration of this thread is that it COULD be a cable issue or it COULD be a misconnected vacuum issue. Without more info about what specifically has been done to your car, it's hard to provide useful info. Any suggestions are just shotgunning. Read the manual, look at how the A/C system works, and figure out what is not correct on your car. I still have no idea how it would even be possible to reverse the operation of the slider cable.

Fun71

I agree. There just isn't any way for the cable to reverse the opening / closing of the air blend door.

Remove the vacuum hose from the heater valve on the rear corner of the intake manifold and measure the vacuum at the end of the hose with the temp slider in the WARM position and in the COOL position. This will confirm which way the vacuum signal is working, and that can be used to ensure you have a heater control valve that matches the vehicle's vacuum operation.