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AC works on passenger side only


sevillebob

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I have lots of cold air comming out of the passenger side vents on my 98 STS. The drivers side puts out warm air only. I bypassed the hot water lines comming into the passenger compartment so that it goes right back into the engine without even entering the passenger compartment, so I know that the warm air is not heat comming off the heater core.

Still no cold air on the drivers side.

Sounds like one of the trap doors arent opening or the electronic control on the drivers side is not working?

If I shut off the passenger's side AC control button by pushing it in, I get control from the drivers side controller, but I get the same thing, cold air on the passenger side and warm (probably inside or outside air) from the drivers side vents.

Any ideas what's going on ?

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I have lots of cold air comming out of the passenger side vents on my 98 STS. The drivers side puts out warm air only. I bypassed the hot water lines comming into the passenger compartment so that it goes right back into the engine without even entering the passenger compartment, so I know that the warm air is not heat comming off the heater core.

Still no cold air on the drivers side.

Sounds like one of the trap doors arent opening or the electronic control on the drivers side is not working?

If I shut off the passenger's side AC control button by pushing it in, I get control from the drivers side controller, but I get the same thing, cold air on the passenger side and warm (probably inside or outside air) from the drivers side vents.

Any ideas what's going on ?

There are four electric actuators in the HVAC ductwork buried under your dash. The one you can suspect is the Air Mix Actuator - Driver, but pull the trouble codes to be certain.

I'll ask Bruce to move this to a more visible location for active discussions.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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The system is low on refrigerant - it is a textbook case with the dual zone systems...The pressure readings will indicate normal pressure yet the system is still low on refrigerant.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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The system is low on refrigerant - it is a textbook case with the dual zone systems...The pressure readings will indicate normal pressure yet the system is still low on refrigerant.

Kevin, I didn't realize that. Just add a can I guess eh?

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Yep - the only positive way to evaluate the refrigerant charge is to evacuate it, weigh it and compare it to the specification label on the accumulator.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Thanks very much guys for the infomation. I'll check out the refrigerant charge and get back to you.

Bob

That did it. By the time I had 10 oz. of Freon added, I had below 40 degree air coming out of the drivers side vents. I put the rest of the 12 oz. can in. It's running great now.

Thanks very much for the help.

Bob

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Now that HAS to be the strangest failure mode I have ever heard of! Good one I suppose, because you're never without some cold air......and if it failed on the passenger side first, you'd tell her she was crazy! :D

Never underestimate the amount of a persons greed.

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Um...yeah. I have the same issue with my 2001.

Right now...I need to add a can about every 6 months. Drivers side starts getting warm. Just added a can yesterday...I think it is the rubber hose leaking a bit...

Anyway, when I first started checking air doors etc...on a hot day no less...after a couple of hours found this little item in the GM online manual....

"Does the discharge air temperature between the right and left center I/P outlets differ by 2-3 degrees?

The A/C system is under charged but not enough to show a difference in low or high side pressures."

Note the part about the pressure will show normal....

Arrrggg...30 minutes latter car is fixed with $10 can of R134....

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  • 1 year later...
  • 1 year later...

I have added 1 to 2 cans of freon and cheap AC gauge says within acceptable pressure range etc. I respect your opinions but I cannot see how my passenger sde registered 48 degrees while the driver side registered 70 degrees and it be a freon issue. I am suspecting a Driver air mix door range issue yet I do not get a code. I pulled the HVAC rear fuse for over 1 minute as suggested in my GM service manual to recalibrate actuators but it didn't help.

A little background. I bought my 2000 Cady DTS used and I have a bad mode door actuator. I get the code for the mode door. When I got under there it was unplugged (paid dealer $100 to tell me it was a bad actator with scan tool but actually was unplugged) and the vents where stuck on front vents. I plugged it in and when I started the car and it goes through its initial check I hear a clicking noise. If I push on the area of the actuator (as best I can, it is a bear to get in there, especiialy on a DTS with center console as the floor vent blocks what little opening there is) I can get it to move through the full range when i push on it. But next time it binds/motor fails again without my help. I am torn between actual motor issue or wheel or arm or door binding. I put it on defrost for winter and unplug it and front vents in summer and unplug it. I did buy a motor for $50 and is too late to return so I should just replace the mode door actuator and see what happens. I saw a post on another site that reccomends removing the radio for DTS owners so a screw can be removed and the floor vent moved a bit to the side for access to actuator. I have a handle on the mode door issue but not the gumption to try it, just now found out about the radio access trick so am encouraged. If the motor turns and then clicks and I press it and it will switch to all different vents with manual help of my hand is that the actuator or is that something binding in the cam??? Like I said I own the motor now anyway but still feel it is binding not motor. Some on forums claim clicking noise is motor. I feel noise may be binding not stripped gear. I have seen instructions for actuator replace only that are hard enough, seems impossible to witness cam and door movement as it is dead nuts behind center console. But I degress.

The reason I posted here is because I have the air mix door issue as well now with large variation of temperature between passenger and driver with passenger working like a champ. when I observe the air mix actuator there is a small yellow paint dot on it so the movement of the center shaft of actuator movement range can be observed. I am wondering if that is factory yellow paint dot or someone has already been under there before for repair or diagnostics? Well anyway I start the car and watch the movement of the air mix door driver. When I turn to hot temp or watch initial cycle the dots line up. when I turn AC to 60 I see the actuator shaft move, no clicking noises etc. (The Mode door actuator is unplugged sent for dash vents) The shaft turns and the range of the shaft is only 90 degrees. On hot setting the driver and passenger temps are relatively equal.

If the hot setting is at 12 oclock when I switch from extreme hot to full cold the shaft only moves to 9 oclock. Is this a full range of air mix door or is it too short of a turning range range causing outside air or engine air to mix and nullifying my AC. Does anyone know the total expected range of the shaft for this driver air mix actuator?

Also I have read that the cam and arms between the air mix and mode door share some parts. Is it possible that the mode door issue and unplugged actuator may have a indirect efffect on the air mix door range?

Also if I have a range issue why do I not get the code for the air mix door inoperable or door range error?

Hate to go to AC guy and have him evacuate system and refill for big bucks only to tell me the AC is fine and I still have warm air on driver side.

Any suggestions are apreciated. Thanks in advance for the help.

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You cannot tell the state of refrigerant charge with those crappy low pressure side only gages from Walmart. I wish they would not even sell those things... The same holds true for snake oil A/C sealer... With those low side only gages, it is very easy to keep adding refrigerant to the low side and have the high side approach 350 psi. All the while, the stupid low side only gage says OK yet the high side is in danger of enabling the high side cutoff switch.

I would recommend that you have someone with a true manifold gage set (that has high and low pressure gages to monitor both sides of the system) check the pressures of the system. If the pressures are within the acceptable range for the given ambient temperature and relative humidity, then I would suspect an actuator issue. The easiest thing to do is to verify the proper amount of refrigerant - either with a manifold gage set or have the refrigerant recovered and weighed to determine the exact amount in the system and then charge the proper weight of refrigerant into the system. The recover/weigh/recharge is the most accurate method. Checking pressures is an approximation that will get you close.

Once you establish that the proper amount of refrigerant is in the system, if it is still warm on the driver's side, then look at the actuator doors. Unhook the linkage rods from the actuators and manually move the doors to make sure they aren't binding. With the linkage rods disconnected and the system running, manually move the blend doors. If the driver's side turns cold, the problem is with the associated actuator.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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  • 2 years later...

will the temp actuator always throw a code? i have no codes the refrigerant levels on the manifold gauge set is rite on. tried adding more with no change, cool on PS the heat will not come on, nor will the modes work. but again i have no codes what so ever.

Matt

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The "actuator" should set a code, BUT if it is working and the linkage is disconnected from it to the door it will not set a code. I think you are going to have to do some exploratory surgery.

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