A/C Basics

[XiKeiyaZI]

When it comes to the A/C system I have a basic understanding of how it works, but considering that it's about to start getting nice and hot I figured I should try to understand it better with our vehicles and figure out why mine is not functioning.

For the record, this is in a 98 Talon, TSI AWD with a 6 bolt swap.

Now, the A/C blows hot as there is no temperature change.
The A/C Fan kicks on and off as it should.
When I turn the /AC button on in the cabin, the A/C Compressor engages.
The entire assembly spins.
If I turn off the A/C in the car, the center of the assembly is stationary.

From what I understand, the compressor will not engage if the system is empty.

When I got the car, the engine was out and the A/C assembly was entirely hooked up and all fittings/connections/bolts were tight. I assumed it wasn't taken apart. Now I figure that it may have been disconnected for a moment and then reconnected.

So, is it true that if there were no freon, the compressor wouldn't kick on?
Since it seems to kick on (but push no cool air) could I simply charge it with a quick charge from a parts store?

Thanks for any feedback.

 

[92AWDHX40]

I think that would be a cheap way to start a reacharge kit from an auto store. I only used the ac a bit when i bought my cars problems arose so i pulled it.

 

[5150DSM]

Typically, if a system is low on or out of refrigerant, the compressor will cycle on/off about every 3-5 seconds, this will generally cause the idle to fluctuate as well. Unfortunately, as in most things this is not always the case. Other possible causes are a clogged expansion valve and a soaked dessicant bag in the receiver/dryer but without manifold gauges (high and low side) it can be difficult to diagnose.

A simple parts store pressure gauge will at least tell you if there is pressure in the system, if so, you can move on to testing the other parts of the system... or farm it out to an A/C shop.

 

[1990boost]

the ac system could be overcharged as well, i work on auto ac and see people do more bad than good adding the small cans to the system as you dont have anyway of knowing whats really in the system to begin with, find a shop and just see if they will evacuate the system for you to see whats in there then go from there.

 

[Insane20]

also if you go to a real a/c shop they will be able to pull vac and charge it the right way, as 1990boost said using those cans can do more harm then good.

 

[1995silvergst]

It is most important to make sure the shop KNOWS A/C, most shops will go to changing parts until it blows cold due to not being able to correctly diagnose the issue. You really need to know what the pressures are as it cycles and how much compressor oil and freon have been put in to start diagnosing the system.

 

[XiKeiyaZI]

Well, here goes a ridiculous amount of money, right?

Starting to see why people just remove AC. You'd think if they blew things apart more by the use of those cans, they'd stop selling them.

 

[91-GS]

As long as it's not manufacturer's fault, they will say that it was miss-used, and keep selling.

Just to clarify, y'all are talking about those cheaper cans with no pressure gauge, right?

 

[XiKeiyaZI]

As long as it's not manufacturer's fault, they will say that it was miss-used, and keep selling.

Just to clarify, y'all are talking about those cheaper cans with no pressure gauge, right?

Ah no. I would certainly want to have a gauge to ensure there's not a high amount of pressure. I know people have had some good luck using them, but at the same time I know some people have messed things up because they fill them up without a gauge telling them there is pressure already.

 

[1995silvergst]

The cans with or without a gauge are a mix of freon and generic compressor oil. Our cars require a specific amount of compressor oil in each part of the system, the FSM will have a set of tests that you can perform on your own to help narrow down possible suspects. The system not only uses mechanical parts the compressor, condenser, dryer and so on, but also pressure and temp sensors along with the ecu to run the system at peak efficiency in all conditions. You really need a set of gauges from an auto parts store at least to know what the high and low side pressures are doing while the system is on and cycles. You can go to a shop and have them do an a/c performance check, however my exp has been with shops that pull a few oz of freon every time. Few oz of freon x 50 cars a week = profit! Download the factory service manual, you will need section 55 pages 1-52 for a/c. Post up what you can about compressor run time length and pressures that you have while cycling and we can move forward with diagnosing.

 

[XiKeiyaZI]

Just updating and tossing this out there for everyone.

Coming home from Taco Bell today I turned on the blower because it was raining and while I knew it wouldn't be cold I figured some nice outside temp air flowing in a car with the windows up being humid would be nice. What came out was just absolutely hot air. I turned it off.

When I got home, ate, and decided to take a shower, I stood there for a few minutes not thinking about anything in particular and then it hit me. I jumped out, ran outside, pulled my glove box - My AC cable was unhooked! I hooked it up, started the car, switched the AC on and turned it to cold : Cold ass air!

Moral of the story

1 : Don't waste money doing something until you've inspected every single angle.
2 : If you can't figure it out, take a damn shower. You can solve all of the worlds' when in the shower.