FAQ: Warm/Hot Air on Drivers Side, Cold on Passenger Side

We are experiencing this issue as well now.

I have torn apart the dash and found the issue. Will post pictures in a bit when done.

Ok Guys, this is for my 95 Rivi. Im not sure what year they changed but the writeup depicts something different then what we have...

This is with the glove box and the computer stuff out of the way,


Some shots of the servo motor location:


The servo motor out of the car:


Opened up:



Pull the missing gear out to turn it easier. Note you need to align the blue gear as shown in the next pictures (I think?):


The correct setup- I think. Its working right. When I plugged it in but not mounted, I went from 60 to 90 degree's. The servo didnt bottom out/bind up. Seemed to be centered well.

These are the pictures for that condition:



What I did was simply clean the crusty hard grease out of it. Cleaned the gears. I only used grease on the shafts and the worm portion (at the motor). Plastic gears dont require to be drowned in grease, they are self lubricating.

Good Job......No Dollar's

Hello, all, i've seached 3 forums and still no difinitive on my ac blowing warm air out the drivers side vents and ice cold out the passenger side vents. 1997 sc riv btw with the passenger control. Here is what i did. pulled an accumulator one at a time and manually turned the blend door shafts to see if i could determine which one would correct this problem (no luck) same problem exsists. looked at each one while changing the settings on the air control panel checking to see if one was not operating but all seem to be working. I've read that there are 3 on the drivers side and 2 on the passenger side but I found 3 on the drivers side and only 1 on the passenger side. is what i found corrrect or is there another one somewhere that i dont see?
This is what I found out by checking each one with ac on:
passenger side==when i turned that one heat out vent then cold air
drivers side (lower right it was what directed air to windshield,mid and floor.
drivers side middle===hot air out vent d side then cold air driverside
drivers side top left=== I believe is for the windshield.
anyways, I see alot of people have this same problem but no real solution to what to do to correct it and I didn't have any luck with it either so feel freee to give me your 2 cents.
thanks Frank

I wonder if the HVAC head (control unit in the dash, with all the pretty buttons) or the pass control has a problem? Wasn't there a service bulletin on those things some time ago - or was that for the display going blank? Maybe someone with access to the TSBs can comment.

Do you have/can you get access to the factory repair manual? There is a great troubleshooting guide in there.

Albertj

Frank if you set the climate control to 90 what happens from the vents? likewise when you set the climate control to 60?

i also have a few problems that i believe may be related to these air mix doors.
first of all, after i installed the diode mod sometimes when i start my car i hear a clicking from the dash. ever since that happened the first time air only blows out of the mid dash vents, no floor, no windshield. after reading a bit i have come to the conclusion that one of these servos on the drivers side is probably shot, am i right?
also, the passenger climate control hasnt worked since i got the car. it doesnt matter what temp you have the HVAC head at you cant change the passenger side temp with the slide switch. does this symptom sound like another mix door or is this a completely different issue?
im almost wondering if theres something wrong with the HVAC head and the diode mod just pronounced it because ever since last winter on occasion the HVAC head will "reset" to the AUTO setting at 75*. that problem doesnt really bother me but not having warm air at my feet and not being able to de-fog my windshield sucks.
thanks for any help in advance.

deekster/caddy, the heat is working 100% when i put it on 90. right now i need the ac and warm air is blowing out the drivers side.

what happens when you put it to 60?

Did you see the link that AA provided regarding this, a few posts down:
https://rivperformance.editboard.com/interior-f20/faq-hot-air-on-drivers-side-freezing-on-passenger-side-t1867.htm#18800
Don't know if this helps any but it might.

i have a 95 riv and the heat on the passenger side does not work...the heat works perfectly on the driver side but blows out ice cold air on the passenger side any advice or ideas?

Have you tried pulling codes from the BCM? The car will store codes, but not set a dash light. If anything, the HVAC controller display will flash on initial startup for about 100 seconds or so if it detects a problem. You will need a Tech1 scanner (or equivalent) in order to pull codes and/or test all the HVAC actuators properly.

Does the air temp change at all with the Pass side controller?

It sounds like the Pass side Blend door is stuck shut blocking off heat from the heater core.....If I'm not mistaken, that actuator is behind the glove box, on top of the heater case.

yea i've scanned it and no HVAC codes came up, i didnt check behind the glove box though...i've heard it could be like the air distribution unit or something like that. so if i take out the glovebox it should be behind there? and i just have to find the stuck blend door?

Well, yes......if you remove the glove box, you can see the heater case. There will be an actuator (solenoid) near the top of the case. I don't have a picture of it, but there are 5 wires going to it. They are Brown, Gray, Gray w/black stripe, Dark Blue, and White w/black stripe.
Remove the actuator.
Start the car, and operate the HVAC in all the modes, including changing the passenger side temperature. See if the solenoid works.....if it doesn't, especially when changing the passenger side temp, it's bad (or in rare cases a wiring problem).

Quote :

I wonder if the HVAC head (control unit in the dash, with all the pretty buttons) or the pass control has a problem?

I think this could be a possibility. I used to have this problem sporadically, but I'm not noticing it since I got a rebuilt head unit.

Any results yet?

lol no, i havent gotten time to wrk on it yet, i've been too busy with other peoples cars

apu711 wrote:

lol no, i havent gotten time to wrk on it yet, i've been too busy with other peoples cars

Sucks doesn't it? I deal with that every day

Okay...searched...saw a lot...but... unsure

My 96 Riv needs a new a/c compressor...but until then I recharged the A/C with new R-134. That helped, but for awhile now I've noticed the center vents are blowing much warmer air than the 4 circular vents for the passenger.

Took the glovebox out, played with the actuators...didn't get the center vents to blow cooler... took the driver's actuators off and only saw they either engage the defrost, make the center vents blow HOT air (but NOT cold air!!!), or engage the floor vents.... 1...2...3


I'm stumped...

Passenger vents, blowing nice cold air..drivers center vents (the ones below the radio) blows tepid outside air...

Ideas my friends??

OH....btw...found a new hood and door to replace my crappy hood and rusty door... $40 each at "U Pick It"...aren't salvage yards amazing?!?!?

Natsriv,
I also have a ' 96 and you're describing the very same problem that I have with the A/C - cold air out of the passenger side vents and cool, but not cold, air coming from the center and on the driver's side. I haven't jumped into it yet because I'm not sure what does what yet. Also, in the winter when I'm demanding heat, a strong leak of outside air leaks in under the dash on the passenger side (right in line with the passenger's left shin/knee) which I think is somehow related. The passenge temperature control doesn't affect it. The first step in my mind is to understand the schematic in the FSM so that I know what doors should be open/closed when I'm calling for A/C and I haven't done that yet.

I noticed this problem not long after I changed out a dying battery and wonder if the disruption in voltage to the HVAC controller didn't "confuse" the computer as to what the position of the actuators is. Does anyone know if replacing the battery could cause a problem like this ? It seems to be a very common problem with this generation Riv.

PS - I've read this thread a couple of times and either I'm blind or the info I'm looking for isn't in it. For instance, say I get a stuck actuator working and reinstall it. Will it index to a default position commanded off some controller start-up command or do I need to manually index it to the correct position based upon what the last setting of the controller was ?

I'll try to go into the FSM this weekend and figure out how it's supposed to work.

I've got an FSM too...it's vague..

But I recently removed each acutator individually to see if one was perhaps broken (gears worn or something)..they all appear to work fine (connected the motor to a 9V battery... moved. While I had each acutator off, I moved the flap each is supposed to move to determine what does what.)

On the passenger side, as I recall, there's 2 acutators... One on the far right, opens the outside air vent, the other, next to the center console, opens and closes the passenger vents...

On the drivers side (#'s 1,2,3 in my in previous post)
1 opens the defrost
2 makes the center vent HOT or ...tepid cold. I suspect this is what turns when you turn the temp up or down
3 opens the floor/mid vent


So none, except perhaps the one on the far right passenger side which opens and closes the outside air is involved...

As you said, I need to determine how the acuators work together from the FSM, it's homework...I thought I could figure it out....but I'm stumped!

Anyone have the same? Is the 97+ Riviera different???

Okay, I went back out again, and did some more (and less flustered) looking at how our airlfow system work.

I've got a Factory Service Manual and it has an interesting picture in it, along with the writing on the workings..I think really any problem we have with the passenger side/drivers side heat/cold may be related to only two acutators.


Gate #2 is the one that's connected to the #2 acuator shown in my earlier post above. That controls the temp of the drivers side vents. It says in the FSM that air is diverted through the heater core (#5) to get warm to hot air. Of course, for maximum cooling the air door on #2 should be closed entirely. A blend of air going through the evaporator (#1) and the heater core (#5) gives you the full range of temps....

What I think happened in my case, and maybe others with the reverse problem is that our actuators aren't fully opening or closing these vents... I'm not entirely sure if our PCM's run the actuators enough that the system "learns" the range those actuators need to run....but I had to adjust my drivers side #2 actuator to get it to cover the full range...see pictures below

Let's explore the actator deeper and you'll see what I mean....

Okay, when you remove an actuator and look at the back, you'll see the metal portion covers the actual white plastic piece of the vent door that is sticking out of the a/c module.

Okay, look at the notch piece there sticking out by the blue arrow on my thumb. See how it rides in the recess of the black plastic actuator cover. It can only turn from one stop to the other stop (the orange arrow).

I found that on my driver's side the metal wheel with the notch was not going the full range. It would turn all the way to one stop easily (and appear to actually "bind" a little") when I turned the temperature to hot. But, when I put the temperature down to max cold, it would only turn to the middle..and not all the way to the other stop on the opposite side....what could cause this?

Well, let's take apart the actuator...there's 4 brass phillips screws holding the cover on. Remove them, and you'll access the inside of the actuator.

The yellow arrow is the gear which connects the motor gearing to the metal wheel (the white arrow). The red arrow shows a blue gear which I believe tells the PCM how many revolutions that actuator has turned... This revolution count MIGHT be the reason the actuator doesn't move the full range.

So....
I shimmied under the drivers side dash (removed the black underdash cover, find a place for the light bulb to hang out of the way.. it gets HOT!) and unscrewed the drivers side #2 air mix actuator. Pulled it off the lever and it was very easy to see it's range of movements...

I started the engine with max cooling on. With the actuator still plugged in and hanging free below the dash I turned the temp all the way cool... the metal wheel only turned about half way. I then turned the temp to max high and the metal wheel turned all the way to the other stop, and appeared to actually buckle...like it wanted to turn more, but couldn't. I then decided to adjust the metal part (the white arrow). You need to pull out the yellow arrow gear then without moving the blue gear (the red arrow) pull the metal gear (the white arrow) out at a slight angle and move it towards the direction of the portion of its travel it's not fully traversing. It's only a few gear cogs on the metal gear, so be careful.

Long story short.. Put it all back together and redo the hot/cold test. Ideally the full range should be achieved. Once you have that done you can put it all back together.

Repeat this for the passenger side if necessary. That actuator is located behind the glovebox..You'll have to unscrew four bolts on the bottom of the glove box and do some shimmying to get the glove box out... and the PCM is just held in place by some clips. It unclips easily, and can sit on the passenger floorboard. Then you can take the three 10mm bolts that the PCM cradled in off...now you have easy access to the passenger side temp acutator. BTW. I was don't know how anyone can access the other actuator on the passenger side. This is the one which opens and closes the recirc door...mine was working fine though. Remember, that at higher summer temps, the recirc is automatically engaged when you have the internal temp low enough...

Whew! TO summarize, if you're having a problem with either the driver's or passenger side blowing hot or cold, it's most likely only two actators. The #2 driver's side actuator or the passenger side actuator which is behind the glovebox, near the a/c assembly; And that it 's possible that they aren't travelling the full range of thier movement (why this would be...I'm not sure)

OH, AND ONCE YOU REMOVE AN ACTUATOR IT'S KINDA HARD TO PUT IT BACK ON, IT DOESN'T WANT TO FIT BACK ON THE WHITE PORTION OF THE FLAP STICKING OUT. I FOUND THAT IF YOU DO THE ACTUATOR TEST AGAIN, AND TURN OFF THE CAR STOPPING THE ACTUATOR WHEN IT'S 1/2 OF THE WAY IN ITS TRAVEL YOU'LL HAVE A MUCH EASIER TIME PUTTING IT BACK ON...BUT BEWARE...YOU'LL COME AWAY WITH SOME SCRAPPED KNUCKLES AND ELBOWS

MY CENTER VENT IS NOW BLOWING COOL AIR...STILL NOT AS COLD AS THE PASSENGER SIDE...THERE MAY BE SOMETHING BLOCKING THAT FLOW PERHAPS, BUT IT'S DEFINATELY NOT AN ACTUATOR PROBLEM

Something to think about

I would be curious where the metal pin sits after the car has cycled the gear a few times.
Either the PCM will notice something is off and do a recalibration test or if one of your gears are cracked it will just move "out of range" again.
Glad you are getting cool air on the driver side, but i think a tech 2 and or a new actuator might be the permanent fix.

I checked all the actuators, and none of the gears are stripped or missing teeth...

I have noticed for quite awhile that I'd hear that particular acutator acting like it was opening and closing...like it was trying to go one way or the other, but get stuck...then the noise would just stop.

I do think I'll buy another spare from Morad as it's "easy" to replace...if you work in a circus and can contort into an s-curve!!!

I do agree that a normal operating system would be able to reset itself.....

On my '96 I am having the dreaded hotter on the drivers side than the passenger air problem. I pulled the lower shield on the drivers side and watched the servos for 1,2,3 and noticed them going from the lines marked on the servos in full operation I believe. Then I took out the glove box and watched the servo to the left of the computer and it appears to move back and forth from line to line without hesitation. What am I missing?

Thanks,
Paul