Climate control/DVV issues... need guidance

[Supra5MGTE]

Ok, I've read the DVV article, read up on the FSM stuff and heres where I am. I checked the vacuum lines on the engine side; good. even unplugged the Cruise incase it was bad; no difference. I checked continuity like the FSM says to on the 2 coolant sensors by the heater valve; good. I have the dash semi-apart so I can see the actuator behind the radio well. The thing is NOT stable. and I have a clicking, and the heater comes on!!!! I don't want the heater on! If I connect the test connector under the passenger's feet area, that's the only way to turn my heat off. It actually makes the diaphram more stable and the clicking stops. I've narrowed it down to:

-Bad lever switches/contacts
-Bad DVV
-Bad actuator diaphram
-vacuum leak behind dash.

What do I do now? I need a little bit more TECH advise here. thanks.

[CJSREDPRA]

Okay....

Am going to assume that you checked the usual sensors that can cause this problem as well...

1. Ambient light sensor is plugged in (the one on the right side of the dash) & it has the dark, but see through plastic cap on it??? Or is it missing???

2. Ambient air sensor underneath the console is plugged in & running??? (It attaches to the little vent that is above the rear ash tray).

3. There is another sensor/probe like thingy (I "think" it's for light) that is behind the front grille. This is plugged in????

[RedP85]

(Chris, the thing attached to the power steering cooler loop is the outside air temperature, called Ambiant sensor in the wiring diagram.)

My guess is that at the normal comfort zone of the actuator the feedback position potentiometer is dirty/bad contacts.
The AC amps try to maintain the requested position, but can't, since feedback has a poor signal.
By changing the color of the 'adjustment' wire white or red, instead of the orange one, you might be offsetting just enough the servo loop to control
in a more stable area (less dirty/bad contacts). Try them out to see the result.

Hope you could understand my suggestion!

[Supra5MGTE]

haven't checked any of those. the dash one I knew about, but thought it and the rest of these type only affected "AUTO" usage. I've never heard about a probe behind the front grille. Where exactly???? News to me.

I'll try using different settings on the color wires deal. Right now.. I have the thing hooked up to the BLUE test lead or whatever like the FSM says. stops the clicking and the heater is OFF!! I'm running the A/C right now in FL, and parts of the country are under 3' of snow.. go figure.

[CJSREDPRA]

haven't checked any of those. the dash one I knew about, but thought it and the rest of these type only affected "AUTO" usage.

Nope...

If any one of those, OR a combination of those 3 are somehow disconnected in someway (ie: it's out of the loop/chain in the Auto A/C system), REGARDLESS if the fan switch is on Auto, Lo, Med, or High, it's enough for the DVV box to go bananas.

PS. Thanks for the clarification on the front sensor Jocelyn. It's been awhile since I remembered what that sensor is. Outside air temp.

[Supra5MGTE]

Oh man. I have the console out currently. so that's 1 sensor unplugged for sure. and the front end of this car has been replaced too, so i'm guessing it's fubared also. Uh. Thanks.

[RedP85]

console disconnected = heat !

[Supra5MGTE]

that would explain the heat then. I pulled the console, heater is always on!!! So we know the console sensor is GOOD. Now to check the other 2 out. Man, I"m learning.... this old a/c stuff is a PITA.

[Rich64N]

Dean A has a writeup on the heater system on his site that came from discussions on the Yahoo group (so, it is a few years old, but our cars haven't changed).
http://www3.sympatico.ca/dean.anderson4/HeatingSystem.htm

[Dave A.]

Is rthe clicking from the DVV erratic or more like a click that you hear every few seconds on a steady basis?

[Supra5MGTE]

the clicking is every few seconds steadily.

[RedP85]

steady sounds like a vacuum leak, either the DVV or the actuator itself.
Most likely the DVV..

[Supra5MGTE]

I checked for the 3 sensors. the one by the p/s cooling loop is there and pluged in. the One on the Dash is broken. the plastic cover is gone. so I'm assuming the Dash sensor is shot.


I checked in the engine bay for vacuum leaks. all is good. so how do I check for vacuum leaks in the DVV and Actuator?

[RedP85]

Cheap way:
connect a hose to the device, create vacuum with your mouth, slide the
hose to your tounge and wait....if it stays for a minute, no leaks...

Real way:
vacuum pump, isolation valve, vacuum gage....you know how to do that !

As for the solar sensor (top of dash) I don't think it would prevent the heating to work completely, it should only offset the heating or cooling coming in the car.

[Supra5MGTE]

10-4. will do.

[SilverMk2]

Take the selector switch unit out and clean up the contacts. I had to switch to a used one in my car and picked up dash clicking with it.

[CJSREDPRA]

the One on the Dash is broken. the plastic cover is gone.

This is most likely the reason why the DVV is getting noisy. With the plastic cap missing, it's reading in a incorrect amount of light, at least during the daytime. At night, does the clicking noise go away??

Get the cap replaced. Best thing to do is find a intact light sensor in a junkyard, unless someone has a parts dash that they can pull one from.

[Supra5MGTE]

I think it's the dash sensor that's causing havek. I'm also going to clean the selector contacts.

[Supra5MGTE]

I finally got a hold of a Vacuum pump with gauge. Put vacuum to the Actuator and it's fine. didn't leak down, or anything. I put vacuum directly to the EGR... OMG. Nothing. I can blow/suck like theres nothing in the way. I need an EGR bad. I played with the HVAC a bit today. Looks like I only get clicking if the Temp position is in certain spots. So I"m going to pull the control panel and clean the contacts up. I think that's the cause. along with maybe a half-good dash sensor.