School me (AC SYSTEM)

[James]

One thing I never took the time to learn is about car AC systems. About all I know is its belt driven and I turn the knob and it should work.

I know know what parts are under the cash and what they do I don't know what parts are under the good or what they do.

I'm not looking for a silver spoon answer but if someone has some good reading material on automobile AC/heat systems please pass it on to me.

Bonus points for Galant specific info

 

[LIV4PSI]

How it works: car a/c

YouTube: how auto a/c works

 

[ktmrider]

HVAC is HVAC, only real delta between home and auto is size ( sometimes refrigerant type too ).

Condenser, compressor, evaporator, accumulator, expansion valve, high and low pressure, gas/liquid, physics still the same.

Closest to GVR4 specific is that it originally came with R-12. R-134a is the preferred flavor right now due to Ozone depletion/holes.

 

[Barnes]

Noes! Gotta run dat propane refrigerant. R-134a creates too many global warmings. /ubbthreads/images/graemlins/frown.gif

 

[James]

I remember why I never learned it.

No lie I fell asleep reading that page. I didn't set my alarm for work. I didn't put my phone on the charger. I didn't even take my pre-bedtime sh*t.

Woke up 15 minutes before I had to be at work with a dead phone and needing to sh*t.

 

[prove_it]

Lol, don't worry, I've been there. Usually it hits me as I lock my door.

I wouldn't bother learning the details of freon state of change and the physics of how it works. In the real world, 90% of problems are either a lack of charge from a leak or a mechanical failure, like a bad compressor or clutch. Rarely, if ever, do I see something that requires me to consider the phase of freon to determine where the fault is. I wouldn't get too determined to understand all the physics behind it.

 

[James]

I can't wanted to learn because I'm going to have to install it soon. And the car has nothing underhood as far as AC is concerned.

Though... Someone just text me interested in buying the car /ubbthreads/images/graemlins/dunno.gif

 

[Barnes]

If you sweat, and you know that evaporating sweat makes you cool, you basically understand AC. AC does the same exact thing, just that it uses a special fluid (freon) that can be made to evaporate in a more controlled and favorable way for A/C systems.

 

[prove_it]

Basic system functions like this:

Freon stored in the system starts in the compressor as a low pressure gas, the compressor compresses the gas to a high pressure high heat gas. This gas then travels through the receiver dryer (which acts as a filter) then travels to the condenser which removes lots of the heat and leaves the condenser as a low temp high pressure liquid. The freon then travels to the expansion valve where it changes to a low pressure low heat liquid , as it leaves the expansion valve it travels to the evaporator. As the freon changes states it is quick to absorb the heat in the airflow across the evaporator and reaches temps of around 35-50 degrees. Airflow over this is cooled and passed on to the vents. The freon then travels back to the compressor as a low pressure gas to repeat the process.

 

[Barnes]

You might want to re-read your post. You mixed a few things up. /ubbthreads/images/graemlins/crazy.gif

 

[prove_it]

Oopps, better go get me some more coffee. I think it's right now, lol. See I don't even think about the physics of how it works, cause you don't really NEED to know the details of it to troubleshoot it.

 

[ktmrider]

^^ Yep you did ( but the picture is worth a thousand words ). Compressors don't like liquid, can you say hydrolock?!?

I also disagree with not "having" to understand the various states, makes diagnostic much easier with a few tidbits. Knowing your High and Low Pressure states makes troubleshooting issues more precise.

 

[prove_it]

Yea, it helps, but really it comes down to charge, pressure levels, and mechanical issues. In the acura/honda world it's almost always a compressor clutch failure, relay failure, or low charge from a leak.

 

[slugsgomoo]

Quoting Barnes:
Noes! Gotta run dat propane refrigerant. R-134a creates too many global warmings. /ubbthreads/images/graemlins/frown.gif



Not to mention it's f***ing worthless. You might as well turn on the vent or roll down a window. R134a is "cooling" at best, R12 or propane will blow ice crystals at you. If it's hot enough to need a/c, it's too hot for R134a IMO.

But deleting a/c is best because then your engine bay has so much more room for activities. /ubbthreads/images/graemlins/laugh.gif

 

[ktmrider]

Quoting prove_it:
Yea, it helps, but really it comes down to charge, pressure levels, and mechanical issues. In the acura/honda world it's almost always a compressor clutch failure, relay failure, or low charge from a leak.

Not trying to dead beat my point, Subaru models suffer from ganky Expansion Valves ( orifice shaft can pop out of the guides and stick ) and knowing that High Side going High and Low Side going Low at 2500rpm = EV replace. And at idle all pressures are/were good.

 

[prove_it]

I'll keep that in mind next time I touch a subie. Good knowledge.

 

[DynastyLCD]

Quoting ktmrider:
Quoting prove_it:
Yea, it helps, but really it comes down to charge, pressure levels, and mechanical issues. In the acura/honda world it's almost always a compressor clutch failure, relay failure, or low charge from a leak.

Not trying to dead beat my point, Subaru models suffer from ganky Expansion Valves ( orifice shaft can pop out of the guides and stick ) and knowing that High Side going High and Low Side going Low at 2500rpm = EV replace. And at idle all pressures are/were good.



in Kia land, our compressor's bearing's fall apart and sound like a power steering pump with no fluid in it. i've seen only one evaporator changed so far. had more wiring issues than sensor failures. the hybrids use a totally different system, even the compressor oil is different.

the above is great knowledge, especially for anyone who works in an independent shop, or on used cars.

keep it simple James, check for leaks and function pretty much. make sure everything's plugged in, make sure it holds a good vacuum, and watch for the compressor to kick on and off.

 

[prove_it]

In GVR4 land, I still have an R12 charge with no replaced componets in 21 years. Pretty awesome IMO. Still blows down to 38 degrees. I had to charge it finally this summer, but I only needed 3oz. I have a small leak at the bulkhead. Most problems I've seen with an unmolested car is leaks/no charge.

Mitsubishi built our AC systems right. The one part of the car that seems to be truly bulletproof.