Chevy & GMC Vans

I've got the front and rear A/C units on my van. I had the system rebuilt and updated to R134 system two years back or so.
At least I think it's R134, I may totally off base here, but I know it's not the old R12 freon.
The system never has really blown what I would call cold air, even when it was new.
The compressor is cycling on what I consider too frequently, but I know squat about A/C systems.
Is this a sign that the freon pressure is low?
Is adding freon to the system something I can do in my driveway (legally)?
Why is it the front system will not blow cool air unless the rear system is turned on?
I've heard radio ads about something called perma-frost that can be added to the system that supposedly drops the air temp by 10 degrees. Anyone used this or something similar? does it work?

Last question: Looking under the hood this afternoon it dawned on me that none of the A/C system hoses have any insulation or foil tape on them. They get pretty well heat soaked in the tight engine compartment. This can't be helping things. Should any of the hoses be insulated?

I recommend that you buy a set of cheap guages like these http://www.harborfreight.com/cpi/ctaf/d ... mber=92649 so that you know what pressures are going on inside your A/C system to help us diagnose your problem further.

Your freon is probably low, and you can top it up on your driveway legally.

If you can post some hi side and low side pressures of your A/C system using the guages, I can help you further......

Cool Thanks SoCalli. There's a harbor freight store near me. I might try autozone or some other parts store too.
harbor freight has some good stuff at cheap prices, and some unmitigated junk. The worst part is a trip to harbor freight is about a 2 hour undertaking once you get there. Store's really disorganized, the staff is moronic and disorganized, the lines are long due to really really slow checkers.
BUT, I don't particularly like to sweat out my work shirts. So I'm all over that.
going to get the gages tomorrow. And this isn't an emergency, I deeply appreciate all help.

I enjoy to beable to help, and share my knowledge with my fellow members.

A/C repairs normally range from $250 - $1500 in my shop, so buy these cheap guages and they will save you hundreds of dollars in repair bills.

Get back here when you have your guages

SoCalli V8 wrote:I enjoy to be able to help, and share my knowledge with my fellow members.

Yeah, like partying near some freakin' lake is help....

If it's hot outside, your a/c shouldn't be cycling. It's low on refrigerant or there's an obstruction in the orifice. My money's on the system being low on refrigerant

three questions...

1) if the directional output of where the air shoots is on the defrost (windshield) does this not cause the compressor to cycle regardless of the temp setting?

2) where is said orifice located?

my 99 had great AC last season. this year nada. I recharged and it obviously is leaking somewhere. when I do recharge it it runs cold for few hours. (yes, i did try a sealer and the recharge).

3) what and where is most common to leak?

Common spots are where the low side line from the rear goes around the driver side of the engine/transmission, that can rub through. I had the high side line whre it clips to the body on the passenger side at the wheel well corrode through. Rear line in the rear wheel well was replaced while under warranty.

The compressor belly seals leak too, replaced the compressor last year with an ACDelco reman, and this year it was empty again.

Those sealers in a can, and additives to lower temperatures generally do not work. And the leak sealers will clog out the system. The oriface tube is located in the high side line by the front evaporator. You will see a slight kink in the line just below the fitting before it enters the evaporator.

If your cycling at idle-1500 rpm when its hot out then you are probably low on charge. Gauges will show this for sure.

Scott

The a/c system contains a small amount of oil maybe 3-6 ounces or so. So to find leaks look at every joint of every hose with a flashlight for an oily build-up that dust or sand may have stuck to. Also look closely at all the fins of your condenser for oil wetspots as they can get damaged from flying stones, the compressor can leak inbetween the housing and the front clutch. There are 'O-rings' at every hose joint that may need to be replaced.

hope i'm not totally jacking kings thread here. being that he hasn't replied in over a couple of weeks on it .... i figure, title and questions and answers may end up being helpful to others with AC issues.

i checked the lines from front to back and back to front. no obvious leaks that I can see. here is something interesting that I discovered. no even on the condensor.

as i drop a can of charge in the accumulator gets cold as it should. the lines going to the rear are cold and sweating. the rear air is cool. not cold but cool. the front doesn't get cool. the front lines are not cold, the accumulator warms up the longer the van runs.

Do you know what pressures you have in the system on the high and low side?

A cheap set of guages like this can save you hundreds on a/c repair, because diagnosis is guaged on what pressures that you have. http://www.harborfreight.com/cpi/ctaf/d ... mber=92649

i am going to see if i can run out and get some in the morning. we aren't lucky enough to have harbour freight in canada

I'm not an AC guru but I have a fair basic knowledge of how AC works. I've seen orfice tubes plugged up with junk. Is it posible that the orfice tube can be plugged and only allow the rear AC to function?

well.. much to my dismay the gauges aren't required just yet. as of 5hrs after the charge was done and only rear blowing cold. the system is empty again. no cold in rear.

i traced the lines to the back.. and again to the front.. still can't find any leaks.

looks like this one will make me open my wallet, bend over and be at the mercy of a shop to find and repair the leak. if it were me driving it all the time i'd leave it. this one is the one my wife drives and being she is still recovering, when she is in the van she needs the AC. right now it's 'as much required' as my fuel pump was.

Wow 5 hours thats a large leak and should be pretty easy to spot.

If you don`t see any oil leaks in the lines or joints or compressor go to an a/c shop and have them use their freon sniff tester to chech for leaks in the front and rear evaporators, up the drain tubes.

crash, which van is this on? Did you find some gauges? What refrigerant did you put in it?

Scott