A/C in a 99 Vette
 

My 13 year old Vette is still hanging it there, running pretty strong. But, as usual, my A/C is acting up......again.

A while back I had the A/C 'coolant' checked and some was added. They said there was a dye in it so I guess that's so you can detect/see leaks? Admittedly I can't see anything but maybe I don't know how to look? or you need special glasses and a special light?

But here is the weird thing this time???? The air coming out of the passenger side vents are/is COLD. The middle vent and the drivers side are warm??? If I sit and idle for a short while the middle and drivers side will start to cool. But as soon as I drive, start moving, you can 'smell' the warmth coming on and the middle and drivers side become warm But.............. the passenger side is cool/cold????? Is this still a sign of the A/C coolant running low? or do I have another problem? I want to be prepared to know what I'm asking or what the tech's tell me what I need.....so as not to be bam-booz-old.

I look forward to your responses

thanks

The leak detector dye may require a special black light to be visible. It sounds like your refrigerant charge is low again, especially since the dye was put in to find a leak.

I would return to where it was previously serviced, so the leak can be found and repaired before the system is recharged with refrigerant again.

:iagree::iagree: You need a black light to see the dye.

Thanks for the response(s)
 

Thanks for the input(s)

My son has the gauges, the 'lights/glasses' and even a machine that can 'smell' A/C gas?

I hope it is just a bad fitting but from what I've read the C5, in my year of car, has been notorious for having compressors go 'south'?

Thanks again.

If you are getting cold air out of some vents, the refrigerant level is probably fine. With low refrigerant, there will be reduced cooling capacity, and little to no "cold" air. Many people mis-diagnose A/C issues, overcharge the system, which puts additional stresses on the compressor as far as increased pressures and can flood the compressor with liquid refrigerant (you can't compress a liquid - something will break).

Sounds to me like a problem in the damper doors in the ductwork. Have you pulled any codes from the DIC?

I had this issue. All I did was disconnect the battery overnight and it fixed it. Give it a try. It's free.

I have this exact same issue in my 98.

When I bought the car, it was completely out of coolant as the AC would only blow air. I charged the system and added quite a bit of coolant. My passenger side is very cold, however the middle and driver side only blows out air, but in 110+ heat, it's not very cool.

I'm thinking that the coolant level is still good as it wouldn't be 1/2 cold if it was low.

The issue has not been fixed and I don't trust any mechanics in the area to start tearing my car apart.

If you search this forum you will find that for a C5 cold passenger side and warm driver side is almost always related to a low charge of refrigerant. It is because of the way the system is designed. It could also be an actuator but you should get a code set for this. Have you used the dic and checked for codes?

My codes are clean.

Do you think I could take it somewhere and try to have the leak patched?

Check for HVAC codes... If you do have a bad driver's side actuator it is much easier to change then the passenger side. If you do have the left actuator code adding refrigerant won't do a thing for you. You will have to reindex or replace the actuator.

Most likely you are once again low on freon.You need to have it checked if you do not have the tools to do it yourself.

:toetap: Not true at all.This is a common problem with the C5.Do a search.

I'd just once like to hear someone explain (logically and technically) how being low on refrigerant can cause one side to be cold and the other side blow like a furnace.

Bueller? Anyone? Bueller?:lol:

I don't know but the 98 C5 I had first would do that when itwas loe on freon.

I read on another thread about a reason.

The passenger side ac comes through the bottom portion of the evaporator while the driver's side comes through the top side. When the refrigerant is low the bottom of the evaporator has coolant and the top doesn't so the bottom (passenger side) is cooler.

I have no experience with AC issues, but that is the only explanation that I found.

[QUOTE=QCVette;1581300828]I read on another thread about a reason.

The passenger side ac comes through the bottom portion of the evaporator while the driver's side comes through the top side. When the refrigerant is low the bottom of the evaporator has coolant and the top doesn't so the bottom (passenger side) is cooler.

Exactly right!

If the refrigerant charge is low, the evaporator will not become "flooded" with refrigerant. This will leave the top of the evaporator empty, and therefore affect the driver side discharge air temperature.

Had the same thing happen in my '01. Passenger side cold, Drivers side warm. I'd check the pressures, and always had to add a can. 2 days later, the drivers side would be warm again. It would only leak enough that the passenger side would be cool and the a/c compressor would still work. Let it go over a winter and it would still engage the compressor and passenger side would cool. Put in a can with the dye in it and the compressor was leaking (there's a post on here on how to replace the compressor, not too bad, just time consuming)

You can sometimes find cheap blacklights at novelty stores. Wait till it's dark out, and look at the various A/C components, lines, fittings etc. The car doesn't need to be running when you do this - the dye stays on the surfaces around where it leaks. If they added the dye to the system last time, and there is a significant leak - it will be obvious - even with a cheap blacklight.

Even if you don't see a leak - check the system pressures. You don't need super expensive tools to do this - even some of the cheapie freon add kits that Wal Mart carries come with usable low side pressure gages. If the pressure reading is low when the compressor is running - the freon went somewhere... For now - just add some more refrigerant to get the pressures back up, and the system will work like it should for at least a while.

As for why the system blows cold on one side not the other - have you ever seen a dehumidifier that's lost some of it's charge running - it can literally form a block of ice on the condensor. The ice doesn't always form evenly. As the refirgerant gas moves through the condensor - it picks up energy and hence warms up. Try blowing air through a solid block of ice...

Well,,,,,,,,,,,,, you have to examine how our HVAC system with DUAL ZONE works. The heat coils are always the temp of the coolant. You have a DAMPER DOOR for the drivers side and a DAMPER DOOR for the passengers side.

The damper door allows the air from the fan to either flow thru the heat coil or the AC COIL or a mixture of both.



Your damper doors MUST be fully functional to allow the system to work properly

Like it was recommended previously.. check your DTCs in the DIC and see if you have any HVAC codes. Especially the ones for the actuators.

If you have HVAC DTC for the actuators, it can and will fail during the cycle period and if it fails in the heat position,,,, you get heat

Try this:

Turn the HVAC OFF. Clear the DTCs and listen for the actuators to cycle. If they don't cycle, turn the HVAC ON and see if they cycle. Look in the DIC and see if the actuators error out and set a DTC.

I had to clear the DTCS on mine a bunch of times before it worked normal and stopped throwing DTCs.

LOW R-134


Remember,,,, Our cooling coils are sort of divided in to TWO separate coils. It is possible to be low enough for the orifice tube to spray freon enough to cool only half of the coils before it flashes off and can no longer remove any heat. from the other coil further down the line.

So,,, If your actuators are working properly and have FULL range and you have heat on one side,, it has to be a low R-134 issue

IF you look on the side of an actuator you can see the output shaft collar and watch it move when you adjust it

http://img.photobucket.com/albums/v4...7/DSCF0042.jpg

Sometimes the output-drive shaft gear cracks and causes the actuator to deliver the incorrect air temp of set a DTCs during the cycle portion of the self test when the head is turned on of the DTCs are cleared.

http://img.photobucket.com/albums/v4...brokengear.jpg

The passengers side actuator will follow the drivers actuator and the passengers knob will vary the damper +- 10% of the drivers set temp. That prevents thunder storms between the drivers side and the passengers side!:lol::yesnod:

Having engineered and designed HVAC and refrigeration systems for the last 20 yrs of my career, I highly recommend that no one adds refrigerant without checking both the discharge and the suction pressures of the system with a proper gage set. There is no other way to diagnose a system. Period. Our cars (at least my 2002 Z06) uses and orifice tube for an expansion device. With this type of device, you charge the system based on superheat (the actual temperature of the vapor refrigerant above the saturation temperature at the indicated pressure) at the exit of the evaporator. There are curves in the service manual that you need to match (the curves are generated at various ambient conditions). With too much charge, the evaporator can not boil all of the liquid refrigerant off and can allow liquid refrigerant to enter the compressor (a condition called flooding). Our cars have accumulators to "trap" some of the liquid refrigerant, as there are certain conditions which make the system prone to flooding (low fan speed setting, higher rpms, very low outdoor temperatures, etc). By overcharging the system with refrigerant, you risk the accumulator allowing liquid refrigerant to the compressor, and you will break something. Cars do not hold a lot of refrigerant (compared to a home air conditioner for instance), so the charge level is fairly critical.

If you overfill the system with refrigerant, you will cause damage to the system.

What Bill said is absolutely correct - it is possible for our system to be low on refrigerant and blow cabin temperature air on one side, but it will not be COLD on the other side, but rather slightly cool, as the system capacity (how much it cools in BTU's/Hr) would be substantially reduced. In severe instances, ice/frost can form on the evaporator, but the low pressure switch should prevent that when suction pressures get extremely low.