(2nd Generation) FAQ: Help! My HVAC is cold on one side, hot on the other!

[Casey]

Any good ideas as to why my godforsaken heat doesnt work?

 

I would start by removing and checking the thremostat, but since they're so cheap, you might as well replace it right away.

 

IF the engine is up to operating temperature and the upper and lower radiator and heater hoses are all hot, and your fan is working, I'd say the problem lies with your heater core or the coolant line running to and from it. Have you tried flushing the heater core yet? Have you ever used any leak-stop product in your cooling system?

 

I did just buy a service manual, so hopefully by this weekend I'll be tearing into my HVAC system and determining what is wrong.

[GtipGary]

Nope never flushed it. Never added any stop leak shit either. My fans are manually controlled by two switches in my car. Ive never checked to see if the lower radiator hose is hot. I know that the top one is ive touched it quite a few times recently and it is hotter than hell.

[Casey]

After checking out and taking lots of pics of a '97 CS coupe without the dual zone climate control, it looks like both systems are clos eto identical, save for the control unit and wiring to and from the individual pieces. I see two actuators on both setups, so that kinda bums me out. I was hoping to get rid of those, but I guess they'll be staying.

 

Does anyone have any info regarding the/a diagnostic mode for the HCC unit? You press and hold both knobs in, then you can scroll from 0-123(?), but I have no idea what it all means... I can't wait to get my FSM.

[cutlassdude96]

here you go

 

Position / Description 

-00 Error Codes 
-01 Servo Position 
-02 Servo Position 
-03 Servo Position 
-04 CJ2 Fan Speed 
-05 Servo Position 
-06 Servo Position 
-07 Servo Position 
-08 Servo Position 
-09 Servo Position 
-10 ? ? ? 
-11 CJ2 Vent Mode 
-12 Engine Coolant Temperature -60Degrees 
-13 Actual Vehicle Speed - MPH 
-14 Servo Position 
-15 ? ? ? 
-16 Radiator Low Fan Turn-on Temperature 
-17 Radiator Low Fan Turn-off Temperature 
-18 ? ? ? 
-19 Servo Position 
-20 (Affected by cabin temperature sensor) 
-21 Servo Position 
-22 Sunload Sensor 

Error Codes ( A 2 digit code indicates a current fault. A 3 digit code indicates a historic fault) 

00 No System Fault 
01 or 101 Inside Air Temperature Sensor Short 
02 or 102 Inside Air Temperature Sensor Open 
03 or 103 Ambient Outside Temperature Sensor Short 
04 or 104 Ambient Outside Temperature Sensor Open 
05 or 105 LH Electric Actuator Open or Short 
06 or 106 RH Electric Actuator Open or Short 
07 or 107 UART Serial Data Line Fault 
08 or 108 Solar Sensor Open

[Casey]

Thanks. I really appreciate it.

 

Just got done checking all of the positions and it looks like the -02 servo position is coming up 106, which according to the chart means the RH actuator is open or there's a short. That makes sense, since it's open in the warm position. I ddin't get a 105 error code though, which I should have since the driver's side (LH) actautor is stuck in the cold position.

 

If anyone can make sense of these codes, PLMK:

 

-01 132

-02 106

-03 99

-04 (fan speed) varies, seems to increase as fan speed does, so I think it's OK

-05 80

-06 00

-07 -119

-08 varies from 119 down to 15

-09 -120, -139

-10 01

-11 00 or 02

-12 (coolant temp) working OK

-13 (vehicle speed) working OK

-14 00

-15 53

-16 180

-17 180

-18 60

-19 52

-20 163

-21 162

-22 128

 

What if you get a code for the that's not 01/101-08/108? Is there an explanation for "other" codes? Is there a breakdown of which servos (for example -02 servo poisition) are where or control what?

[Casey]

I got my '97 FSMs yesterday and there is no further breakdown for the above codes and such. I was hoping there would be a explanation of how to test each actuator, but all that's listed is to "replace" the part if it fails the listed tests.

[IRONDOG442]

hurrr :sahurr: :sahurr: :hurr:

 

HOSED !!!

[DrWho]

Question: Does anyone know if you take apart the actuator and move the gears , then put it back together will it reset itself . or will it be all messed up ... I'm hoping it will recalibrate itself , else I imagine it will just break itself to bits.

 

I ask because I took mine apart to check if the gear was broken .. because it was not moving and stuck on cold . and then I took out one gear to allow me to move the main one so that I could set it back to warm ... well its not so warm and I suspect that maybe because a) I did not move it enough and the air door it 1/2 way inbetween blending the hot and cold.. or there is another air door controled by an actuator maybe in the back of the HVAC unit ..

 

btw I have 95 monte carlo with 3.4 LQ1 .. HVAC control is 3 dial type vent selector/fan speed/temperature.. other than the hot/cold being stuck on cold it works .. it was stuck on hot for a while , until I set it to cold a few days ago not thinking and to my suprise it went cold ... and then stayed that way!!

 

all other HVAC controls work , fan speed and vent position .. just the temperature does not change .. and I am guesing its intermittant , because it was stuck on hot . and then it decided to work for a minute and then got stuck on cold .. but cold is no option in winter ..

 

ideally I'd like to get it fixed so works as designed .. so I dont have to manually adjust it cuz its just a pain. any thoughts or ideas will help ..

 

its not the heater core either , I know the heater core is working . not as good as new but I had good heat b4 I set it to cold and it got stuck last week..

 

 

[jeremy]

soooooooooooooo...if my driver side is blowing warmer then the passenger side, do I replace the part on the DS or the PS side?

[shyguy164]

What do you have the temp set at? If you've got it set to the coldest, replace the driver's side. How much warmer is the driver's side vs the PS?

[jeremy]

60* is what I have it set at

 

the driver side is noticeably warmer, not hot but certainly not near as cold as the passenger side is...

[shyguy164]

Yeah, that's the same mine was, just the opposite side as yours. If I remember correctly, the DS actuator is way cheaper and easier to get.

[jeremy]

Thanks for the help!

[IRONDOG442]

The actuators look idenitical to me, and the passenger side is easier to get to.

[shyguy164]

From what I remember when I did this a year or 2 ago on my 95 vert, the actuators look very similar, but the connectors are different. I bought an actuator from somewhere, but had to return it because it had the connector for the DS not the PS. I ended up having to go to a dealership and pay a lot of cash.

[beamrider]

Apologies for resurrecting this, but I've got this problem too. 2004 Monte Carlo, I'm thinking the drivers side actuator is bad, but hoo boy, HOW do you get it out of there? Flex shaft maybe, or a thumb ratchet? If anyone else has ran into this issue, please let me know how you went about removing the actuator, it'd be much appreciated......

 

[jeremy]

Apologies for resurrecting this, but I've got this problem too. 2004 Monte Carlo, I'm thinking the drivers side actuator is bad, but hoo boy, HOW do you get it out of there? Flex shaft maybe, or a thumb ratchet? If anyone else has ran into this issue, please let me know how you went about removing the actuator, it'd be much appreciated......

 

 

<---subscribing...

 

I have yet to tear into mine....but I am curious as to the how to remove it ...

 

 

[IRONDOG442]

Theres three 7/32" brass colored bolts holding it in place IIRC

[beamrider]

Theres three 7/32" brass colored bolts holding it in place IIRC

 

Yeah, saw those when i removed the passenger side one already. Problem I'm having is actually getting to those 3 bolts, and was wondering if there was someone on here perhaps who has the same year/model that's done this procedure before.

[slick]

Unfortunately, there's really no great way to get at them. Contort your body, bend your wrist backwards, and have fun.

[GP1138]

Unfortunately, there's really no great way to get at them. Contort your body, bend your wrist backwards, and have fun.

 

I've had many dates like that.

[axisofjustice9c3]

Does this apply to a '98 Lumina? I bought the car with a locked up compressor, put on another compressor and had room temperature air with A/c on cold, and hot air with it on heat. I bypassed the heater core to see if heat was bleeding in from there, and it was. After a quick bypass it was freezing on the driver's side, slightly warmer on the passenger side. The dual zone was always funny acting (can't really describe), and with the heat bypassed I didn't use it much, so I can't really give much info on symptoms. Suddenly, after three weeks of good cold air (FLORIDA, ugh!!!) it decided to blow ambient air temp, which could be heat as it is still bypassed. The compressor still kicks and runs and doesn't cycle fast (on/off/on/off), so I want to say that since it is all new that it still is working but is having HVAC control gremlins (o-rings, charge, oil, lines, compressor, orifice tube, reciever/dryer all new).

[bmaverick]

This is a common actuator used by GM, some Fords, some Chryslers and often Jeeps. A few of the transplant vehicles use these as well like some Toyotas and Nissans.

 

With that said, these actuators are popular from the late 1980s to the present. The gear guts are usually the same, only the PCBs are somewhat different depending on how the actuator is used. The little blue gear is the pot. Some of these don't have a blue gear pot control and can be easily fix by swapping out the cracked gear from a donor actuator.

 

The large gear that tends to crack at times comes in two flavors; one with a metal wiper contact (w/o blue gear pot) and one without the metal wiper contact (this has a blue gear pot or none at all). So, getting any variant of the actuator and to swap out the cracked gear would save big dollars.

 

If you plan on swapping out a cracked gear, take note the position of the big cracked gear and the position of the blue gear. Then just swap in a new big output gear from a donor actuator by lining up the bump tab if needed to the old position.

 

These actuators are used in other applications as well and/or other industries too. (Sunroofs and rear tail-gate power window) (Solar panel positioning systems, solar water valves and small dish satellite communication receivers) (RV industry for water valves) (Aviation and Marine for HVAC climate controls).

 

Three companies make/made these actuators. One is in TN (Saia-Burgess), the other in Asia (Worry) and the third company quit producing them by the late 1990s (Eaton).

 

These actuators can be had at a reduced price new. Go to any Mopar parts and service counter and order one without the 12m/12k part warranty. This usually cuts the dealer price in half or more. This works best since you get a newer actuator. However, you are buying it "as-is" with no return option. Thus far, I've never been burned with a bad dealer part yet. It's taking chances I know, but I do inspect the package first before leaving the counter. Some dealers will not do the bare part only no-warranty sale, so find one that does.

 

The other option is a bone yard for a W-body or other vehicle that uses these as mentioned above.

 

[axisofjustice9c3]

If ordering from Mopar, what are the equivalent parts #'s?

[mhildebrand]

I have the problem that the passenger side controls in my 96 CS dont do anything.. What ever the drivers side is set to, thats whatthe passenger side goes to. Same with the passenger button selected or not selected. Any ideas on this?