AC Recharge - Did search already

AC on my 98 doesn't blow cold air anymore, and the compressor kicks on/off every couple seconds or so. I went and bought a recharge kit from AZ (quick connect hose with gauge). I turned the truck on, turned AC on max cold, and then connected the gauge to get a pressure reading. It went to about 55 psi. I bought the truck last year and it didn't blow cold air back then, and I've never serviced it. Does this reading have something to do with the compressor cycling on/off? If there is that much pressure, then should the compressor be cycling as much as it is?

Thanks,
Joe

if the compressor is cycling often it is probably low on refrigerant. the system holds about 1.25 pounds. you are still probably low. check for an oily residue leaking around the a/c hoses and fittings, especially the compressor line seals. if no leaks are noticed, you probably have a leaking evaporator coil. that is not uncommon.

jneary said:

if the compressor is cycling often it is probably low on refrigerant. the system holds about 1.25 pounds. you are still probably low. check for an oily residue leaking around the a/c hoses and fittings, especially the compressor line seals. if no leaks are noticed, you probably have a leaking evaporator coil. that is not uncommon.

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a rapid cycle of the ac compressor can also be the high pressure cutout switch preventing the compressor from exploding.
55 psi is a high reading for the low side and adding anymore to it can do more harm than good, but i didnt notice what side you took the reading from.

I still dont understand how parts houses can sell a generic ac kit for all types of vehicles, no 2 take the same amount of charge, and the oils and additives can actually create an "acid" type reaction and destroy the entire system from the inside out!

the low pressure switch only keeps the compressor fromm running when the system is too low of a pressure. the high pressure switch cuts the a/c off when the high side reaches a pressure too high. there is no way to read the high side pressure from a gauge on the low side when charging. i dont know how much refrgerant was in the system, or how much was installed in the generic kit, but without measuring what was in the system prior, i would still believe the system is low on the system charge.

You are where I was a few weeks ago, you have air in the system and it won't take anymore R134a into the system.
You need to take it to a shop, there they will throw a vac on it for about 30 min at around -30lbs or so to see if it holds. If it holds they will recharge the system with a new 134a that has a dye in it. Then they will do a once over looking for any major leaks with a black light and yellow goggles. The shop then should tell you to bring it back in two weeks when they will go over it with a black light again looking for the leak, if any. The 30 min vac will also remove all the moisture and PAG oil in the system, they will put the correct amount of pag oil back in when it gets recharged. I went thru this about 2 weeks ago and will be taking it up to my friends shop to do the black light thing next week. I will be paying special attention to the water drain down on the bottom of the firewall right over the frame rail passenger side, looking for any dye there. If there is dye there that means the evaporator in the heater box is leaking. I'm hoping we see dye on the condensor in front of the rad as that is much easier/cheaper to fix then the heater box one. According to all I have read the tower or dryer should also be replaced whenever the system is drained and refilled or every 3-5 years. Depending on what we find next week I will probably replace it if I need to replace the condensor. If the evaporator is bad I may move on to a newer TJ rather than go thru the cost and time involved with removing the entire dash to replace it. We will see...

Thanks for the input. I hadn't put any refridgerant into the system before measuring as stated above. I took the truck to a shop to check it out before I bought it and they assumed like I did that since the air wasn't cold and the compressor was cycling that all it needed was a recharge. I'll take it to have someone look at it.
Thanks again,
Joe

the best thing to do is have them measure what they pull out so you wont have to pay for freon that was already in the system.then they can put a vacuum on the system to see if it has any leaks, and with a vacuum on the system, it will take the refrigerant easier.