[eBoyDog]

My 93 Grand Cherokee AC hasn't worked since I bought it, with the AC on, the compressor kicks in for second or two and the let's go for minute or two and it kicks in again.

Thought it was low on r134, hooked up my gages and I had about 100 lbs on the high side with 50-60 on the low without the compressor running.

In searching though the threads here I noticed the trick of hotwiring the low pressure harness to make the clutch kick in which worked BUT when the compressor is running the high side basicly stays the same but the low pressure side dropped to zero; weird thing was the low pressure line that goes from the top of the front and runs along the fender back to the inside (same line were the low pressure port is on) frosted up.

With the compressor running I could feel a a difference between the two line coming off the compressor with a warmness on the high pressure line and perhaps a little cooler on the low pressure not a whole lot of difference but some.

When I shut the engine off the high pressure stays stable but the low pressure comes up to about 60-70 lbs, starting the enigine with the LPS jumpered, the low pressure side drops down to zero and I added an 8 oz can of freon and when I intially started filling the low pressure would come up to 10-15 lbs but once the can was empty it would drop back to zero.

I though there might be a leak, but it's been hold the same pressure for more than a month as I have put the gages on it just to check first if there was any pressure in the lines and nothing as changed, I assume if there was a leak with the compressor running or not, there wouldn't be any pressure, right?

Any ideas were I should start, while I'm not a totaly ASA tech, I have worked with AC a little but this has me confused; I have dryer and orfice on order that will be in tomorrow and I figure that's were to first start but any AC guru's out there have any advice? At this point I believe I should replace the dryer and leave a vacum on the system for a few hours and see if it holds that but I would rather not spend the $100 on the dryer if it's not necessary as well, money is tight but summer is coming.

Any thoughts a advice are welcomed.... mind my spelling I think my wireless keyboard's batteries are dieing

[CaseyC]

Originally Posted by eBoyDog

My 93 Grand Cherokee AC hasn't worked since I bought it, with the AC on, the compressor kicks in for second or two and the let's go for minute or two and it kicks in again.

Thought it was low on r134, hooked up my gages and I had about 100 lbs on the high side with 50-60 on the low without the compressor running.

In searching though the threads here I noticed the trick of hotwiring the low pressure harness to make the clutch kick in which worked BUT when the compressor is running the high side basicly stays the same but the low pressure side dropped to zero; weird thing was the low pressure line that goes from the top of the front and runs along the fender back to the inside (same line were the low pressure port is on) frosted up.

With the compressor running I could feel a a difference between the two line coming off the compressor with a warmness on the high pressure line and perhaps a little cooler on the low pressure not a whole lot of difference but some.

When I shut the engine off the high pressure stays stable but the low pressure comes up to about 60-70 lbs, starting the enigine with the LPS jumpered, the low pressure side drops down to zero and I added an 8 oz can of freon and when I intially started filling the low pressure would come up to 10-15 lbs but once the can was empty it would drop back to zero.

I though there might be a leak, but it's been hold the same pressure for more than a month as I have put the gages on it just to check first if there was any pressure in the lines and nothing as changed, I assume if there was a leak with the compressor running or not, there wouldn't be any pressure, right?

Any ideas were I should start, while I'm not a totaly ASA tech, I have worked with AC a little but this has me confused; I have dryer and orfice on order that will be in tomorrow and I figure that's were to first start but any AC guru's out there have any advice? At this point I believe I should replace the dryer and leave a vacum on the system for a few hours and see if it holds that but I would rather not spend the $100 on the dryer if it's not necessary as well, money is tight but summer is coming.

Any thoughts a advice are welcomed.... mind my spelling I think my wireless keyboard's batteries are dieing

First off, your pressures @80 deg F should be 32-41 on the low side and 200-260 on the high.

It sounds to me like you have a blockage in your low pressure line. I am not that familiar with the location of the different components on the GC, but on a Ford that I used to own I ran into something like that. My pressures were way off, the high side was frosting up, but I was not getting any cold air. Turned out, that I had a blockage in the line about a foot prior to the orifice tube (frost should form at the orifice tube but in my case it was about a foot before that). A little of the coolant was getting through and causing the frost. I believe you can get the same symptoms on the low pressure side. Since you are going to open the system, run some flush through the lines and blow it out with compressed air.

Hope that helps,
Klaus Cook
Houston, Texas

[eBoyDog]

Ok, someone's going to give me the what for with regards to my next question but I will ask it anyhow....

Were is the orfice filter tube generally located? I bought a new one and see from it that's a inline in the low pressure line but short of disassembling all the lines, were should I go to find it?

While I'm asking is there a recommended procedure to flush the system, I have a quart of AC flush without the actual "Flush kit", I envisioned simply disconnecting the lines and figure out a way to insert the fluid into the condensers then using compressed air, blow it though and back out. Anything I should be careful of like not using enough or too much pressure including should I run the flush though the compresser as logic tells me I wouldn't want to as to not get the flush mixed into any oil in the compresser?

I'm going to replace the dryer too since I managed to borrow a buddy's 6 cfm dual stage vacum pump to put a good vacum on the system before re-charging it (and to check for leaks before putting freon into it). I'm more familer with residential AC unit's and my automotive AC knowledge is lacking. so any advice would be welcomed short of "take it to a shop that knows what they are doing" but that costs more money than I have for this project and I won't learn anything in process.

Thanks!

[MAUSS]

Autozone has a flush kit listed in their free tool loan program. You pay for it, use it, then take it back for a refund. Jeepair.com has good prices on parts.

[Turbonut]

Normally, just replace the low side line if the orifice is clogged.

[CaseyC]

Good news and bad news.....

The good news....the orifice tube is located in the liquid line near the condenser.

The bad news ....apparently it is part of the liquid line. Here from the Service Manual:

The fixed orifice tube is located in the liquid line
near the condenser. It has filter screens on the inlet
and outlet ends of the tube body. If the fixed orifice
tube is plugged, the liquid line must be replaced.

[YJMCBoy]

It's only happened to me once, and not in a GC, but I have seen that a plug in a liquid line causes the pressure to go way out of whack on the high side. The fact that you can't get your head pressure up (discharge on the compressor) and you say the only difference between the low and high side is temperature (unless you left out pressure too) I would say your compressor is shot.

[Turbonut]

Originally Posted by CaseyC

Good news and bad news.....

The good news....the orifice tube is located in the liquid line near the condenser.

The bad news ....apparently it is part of the liquid line. Here from the Service Manual:

The fixed orifice tube is located in the liquid line
near the condenser. It has filter screens on the inlet
and outlet ends of the tube body. If the fixed orifice
tube is plugged, the liquid line must be replaced.

Good news it's only $31.96:
http://www.techchoiceparts.com/ShowItem/115178%201993%20-%201998%20Jeep%20Grand%20Cherokee%20Liquid%20Line% 20Orifice%20Tube.aspx

[eBoyDog]

Thank everyone for the advice and the link to Jeepair dot com, that saved me big money as I had a auto parts store here in my town order the dryer/hose assembly and while it's here and waiting for me to pick and pay for it, I was able to order the dryer, liguid hose, gasket kit and line quick release tool (which I had forgot all about) but all that cost me $10 more than what the local parts house wanted for just the dryer including free shipping.

Weather is nasty this weekend anyhow, The AC project is going to be put off until next weekend! It's in the lower 30's with forecast of snow and ice for today, unless Missouri weather turns around a hits 90 next week, I have dibs on my buddies vacum pump for a week or two.

I will wait on getting the compressor as it's available locally if I need it there's not a big difference in price locally compared to the internet, I will replace the dryer and liguid line first and see were that leave me as I think my main problem is in the lines and will figure out were that leaves me.

[Turbonut]

Originally Posted by eBoyDog

I have dibs on my buddies vacum pump for a week or two.

I will wait on getting the compressor as it's available locally if I need it there's not a big difference in price locally compared to the internet, I will replace the dryer and liguid line first and see were that leave me as I think my main problem is in the lines and will figure out were that leaves me.

Make certain you run it long enough, and also, don't forget to add some oil.

[CaseyC]

Originally Posted by eBoyDog

I will wait on getting the compressor as it's available locally if I need it there's not a big difference in price locally compared to the internet, I will replace the dryer and liguid line first and see were that leave me as I think my main problem is in the lines and will figure out were that leaves me.

I looked into the service manual a little more; there is a flow chart that sheds a little light on the problem.

With the "cycling clutch pressure switch" jumpered (compressor runs constantly), take your pressure readings. At 70 deg F you should have 26-35psi at the evaporator and 180-240psi at the compressor discharge port. If the evaporator pressure is lower than normal and the compressor discharge pressure is lower than normal, then either the orifice tube is restricted or plugged or the evaporator is restricted or plugged.

Chances are pretty good if you replace the orifice and the dryer and flush the system you should be home free.

When I flushed my system I just poured the AC flush into the component and then blew it out with compressed air until it ran clean (this was on a system where the compressor had died and there were valve pieces and crud all through the system). A small funnel with a flexible hose attached is worth its weight in gold for this job.

[eBoyDog]

Thanks CaseyC, that's along the idea I thought too. The compressor didn't make any bad noises or for that matter so I'm hoping it's fine, as soon as jeepair sends me my stuff, I should be good to go!

[eBoyDog]

Cleaned the system with AC flush, replaced the accumalator and low pressure line, replaced all the o-rings including the compresser gasket on the manifold, sucked out the system with a vacum for 3 hours and everything is good.

It's appears that the previous owner loved the leak detector dye, I never saw so much green fluid except with anti-freeze!

I'm ready for hot days now!