Crimsonnaire

iTrader: (1)

Summer has already arrived here in GA, so it's time for me to get my AC working again. I haven't used it in many years since it stopped blowing cold. I bought a can of R134A and was about to charge it when, to my surprise, the pressure is at approximately 24 psi, which is just a tad off the border line between the green (filled) and blue (empty). Another thing is that it seems like my AC condenser stopped engaging, despite having a relatively new tensioner. So my first question is whether having 24 psi mean that there should still be enough refrigerant for the AC to blow cold if the condenser is working? Or could 24 psi be low enough to the point that *either* the condenser will stop engaging or stop blowing cold even if engaged?

The instructions printed on the can seems to indicate that having a low refrigerant psi could cause the AC pulley/tensioner to not spin...

Any clarification is appreciated.

RockinWs6

What are we working on?

Crimsonnaire

iTrader: (1)

Stock LS1.

The pressure reading was taken from the port on the silver canister at the left side of the engine bay...

If the AC is not blowing cold (warm in fact) even with 24 psi, is it worth trying putting more refrigerant in or does this indicate a problem elsewhere?

RockinWs6

Well I'm going to assume you are working on a Trans Am? Your 1st post is a little off, the CONDENSOR doesn't turn on. The compressor does and IF it wasn't running and you attached the refill canister and only saw 24 psi that's why its not running. STATIC without the engine running if you attached a pressure gauge you would see about 75 psi. That being said I don't want to confuse you because I know you know little to nothing about your ac system.
Read carefully

Start the car and turn the AC on Windows open Fan set to high AC set to outside , attach the refill canister. If the COMPRESSOR is not turning and the pressure is below 30 psi start adding coolant from the refill canister. When the pressure in the system rises above 30 psi the COMPRESSOR should turn on. Continue adding coolant from the canister because as soon as the compressor turns on the pressure is going to drop below 30 and the COMPRESSOR will shut off. Keep adding coolant until the COMPRESSOR stays running and the pressure stays at 32-36 psi.

Good Luck Grasshopper

01ssreda4

iTrader: (96)

If youre so low that you are triggering your low pressure cutout one can probably wont be enough to get it blowing really cool.

Crimsonnaire

iTrader: (1)

Sorry for the vagueness. I had assumed the AC setup would be similar if not the same across the LSX line. But if not then I guess I can't pull AC parts from non-LS1 cars.

Thank you for the instructions. I had completed the steps you listed, and the compressor did engage after filling a little while. However, after the can emptied, the gauge read a tad over 30 psi (this is with the engine and AC running) but the air was still blowing warm. Now if I turn on the AC, the compressor engages as it should, but no cold air. Should I try filling another can or should it already blow cold at this point assuming there's no other problem in the system?

Is it a reliable to assume that if the air still doesn't blow cold even when the pressure is near the high-filled point, I should investigate elsewhere?

hrcslam

Charging the A/C isn't as simple as add some R134a and let her rip. It's low and high pressure (and static: system off) sides will vary based on ambient temps. 30 PSI might still be low, could be just right, or could be high depending on how hot it is where and when you are charging it.

However, 30 PSI should blow colder than ambient regardless of ambient temps (unless it's freezing out). If you are not blowing cold, you have another issue. Maybe the blend door is stuck on the hot side? Maybe your lines are clogged, etc.

What you need to find out is if your blend door is operating properly, if it isn't get it fixed. If it is, you'll need better tools to properly diagnose the problem. You should actually be reading the High and Low sides of the A/C System when charging it up, it can tell you if and possibly where the problem is.

FYI, refrigerant has a direct relation to pressure and temperature. For example, 30PSI is about 35°F, 75 PSI is about 72°F, 160 PSI is about 115°F, etc. Adding more refrigerant doesn't mean it'll blow colder. Usually A/C will blow the coldest at the lower side of full. Putting too little in can cause issues though.

Crimsonnaire

iTrader: (1)

Thank you for the clarification. I decided to do this on a cold start in the morning so the engine wouldn't make everything too hot, but the outside temperature was already in the low 70's. Later this week, it'll reach 90 F! I gotta get out of this place.

Can you tell how to access the blend doors for inspection? Is it somewhere behind the radio? I do know that there's been a lot of dust and debris that the car's been exposed to over the years, and it's been about 5 years that I haven't used the AC system.

By the way, is there any problem if I mix different brands of R134A? After making sure the blend door isn't the problem, I guess I'll try filling in one more can and if that doesn't work then time for further investigation. The system is still able to hold a substantial amount of pressure (24 static psi), so I would think the compressor and condenser are still within operating condition...

hrcslam

24 psi is nothing to an AC sytem, it means there's a leak. Static at 70°F should be closer to 70-75psi. The high side of the AC system can see over 200 psi regularly.

Is not recommended to mix brands, but it usually has no I'll effects.

I'm not sure how to access the blend door for inspection. But an easy way to tell is to crank the heat, then the AC. If the temp doesn't change it is likely the blend door. If it does, but doesnt feel cold then it's likely something else.

We've been over 100 a few times this year, I know how you're feeling. But we lack humidity most days; so we (humans) still evaporative cool, but our cars tend to run hotter because of it.

Crimsonnaire

iTrader: (1)

Correction:

My AC does blow cold!! (This is gonna be embarrassing.) I had neglected the temperature dial on the hot side. It's been so long since I used the AC that the heater and window defroster were the only air functions I used, so I gradually forgot about the adjustment dial. It blows quite cold on both AC and Max AC--what's the difference in compressor operation between these two anyway?

Thanks very much to everyone for the instructions and suggestions!

The refrigerant psi gauge distinguishes between empty and filled at the 25 psi mark, and reaches the high mark at 50 psi I think. Do you mean to say that, at 70 F, the static pressure should normally be in the high zone for a properly functioning AC system in these cars?

Wow. That's just extreme! I think humidity resides up to a certain temperature (usually in the 90's) before being forced up higher in the atmosphere. So I guess our longitudinal spot hardly sees any Spring and Fall. I can stand both hot and cold weather. It's just the lack of consistency in the temperature shifting radically between night and day that gets to me.

Are you able to drive comfortably with the AC off but T-tops off and windows down in your area?

hrcslam

Sounds like you are using one of the cans with a gauge on it. That is to be effervescent only when the car is running with the AC on max. 25-40 would be the target depending on ambient temps.

I'm referencing actual AC manifold guages that show high and low side. Static should be close to 70psi on both sides.

No, I cannot drive with the AC off and t-tops off with temps over 100. The pleather burns my arms. But temp wise, I'm a little hot but ok.

I'm glad you got it working!