Hey everyone. well a while ago i had posted some questions about fixing my a/c that went out several years ago. well i finally had it fixed about a month ago. everything has worked fine until yesterday. I had a mechanic install all the components, new gm compressor, drier, and expansion valve. i wanted to do it right with all new gm parts so it would last for the life of the car. i thought this would be the right way to go. well it worked great until yesterday. after i got off work and was on my way home it would intermittently blow cold then normal air, then cold again, and so forth. it did this all the way home.

when i got home i popped the hood to look to see if the compressor was turning, and it was the whole time, never cycled on or off. When it was idling in the driveway it worked fine the whole time, never blew cold then normal air and vice versa. i decided to see what it would to tomorrow, which would be today. I make my morning commute to work and and it did the same thing almost the whole way. blow cold then normal then cold then normal again. then at a stoplight it stopped blowing cold completely for about 5 minutes or so. i dont know if the compressor was on at this point because my low speed fan wasnt on.

i have a manual fan switch with leds i made like guys on the board here have and i know when the a/c kicks the fans on or not. the led wasnt on and the fans werent going so of course the a/c wasnt working. it did this for a while then after about 5 more minutes of driving the fans just come back on again and the a/c blows cold for a minute or two and then starts blowing normal air, then cold air, again. it did this all the way to work (1 and half hour commute). i got to work and left it running to look at the compressor, and of course it was spinning the whole time. then the a/c seems to work fine and not intermittently blow cold then normal. i dont know whats going on but i do need this fixed asap. i spent a lot of money on it.

i have researched on here and some guys have said the cycle switch or the a/c relay but i think thats fine and its not the switch cause i dont believe the compressor cycles on and off. it might when the fans stopped working but i dont know exactly what it is. on the metal tubes for the low presure and high pressure lines, usually the low pressure is ice cold with condensation dripping off it. well its not doing that anymore, it is somewhat cold but not like it should be with water dripping off of it going to the expansion valve. the line coming from the drier is hot.

is it supposed to be cold or hot cause its hot. is it my expansion valve? compressor? relay? cycle switch? low on freon? i dont think its low cause when it actually does blow cold, it blows cold like it should, not cool air or anything. In other words when it actually does work and blow cold it blows cold like it used to. I called my mechanic and hes thinking an electrical problem but if it was wouldnt it throw a code and ses light? im tkaing it to him monday but its wed now. so i have to wait. but i was wondering what to check for or steer him in the direction so i wont have to worry about not getting it fixed now. if its any of the parts expansion valve, drier, compressor, i have to order than and im not off again till the following monday. i need it fixed asap and i hope to have it fixed monday. let me knwo waht you guys think if any of you have had this problem what was it? thanks

 

Theres a chance that its low on refrigerant. When it was recharged, did they add leak detector dye to the system? That should make it easy to detect a leak if there is one. Mine leaked from the valve core on the low side and it did the same thing you described.
Another thing to check is make sure the fan is coming on when the AC is on. Check the relay and fuse. I serviced the AC on a Dodge ram not too long ago. The compressor was cycling just like it should but it wasnt blowing cold air.
When I recovered the refrigerant, there was the exact amount in the system as the spec called for. I noticed the condensor fan wasnt coming on, checked the fuse and it was blown. After I replaced it, the fan came on and it blew cold air.

Just a few things to check
Good luck

 

Sounds like you have a leak mine did the exact same thing when it was low on refrigerant it would blow hot then kind of cold then hot ect.

 

or for that matter it could have to much refrigerant
and when the pressure gets to high the high pressure switch will kick of the compressor

 

Refrigerant charge needs to be checked by a reputable shop, vacuumed and recharged if necessary and checked for leaks.

 

i dont think it is a leak cause after a while it seems to work somewhat ok. but i dont know for sure. i hope its not a leak, i had my mechanic change all the o-rings for the parts he replaced, drier, expansion valve, and compressor. the fans kick on and the work fine. i have a manual fan switch. if it was low wouldnt it be cool air instead of cold air? it still blows pretty cold when it does work and air coming through the vents. thats why i dont think its low but it is a possiblility. i am taking it to him monday so hopefully he can fix it and fix it for good. i hope it works for the life of the car and not have any more prolbems with it. i spent a good chunk of change on it. it worked great for almost a month until yesterday.

 

If the system wasn't properly vacuumed for long enough, it might be icing up the expansion valve internally. The system needs to be evacuated properly and recharged with the correct amount of refrigerant.

 

doesnt the icing up mean freezing and doesnt that usually happen at stoplights or something? and it means that it will stop blowing cold air until it unfreezes? and blows cold again? so does that mean i need a new expansion valve if its icing up or freezing? thanks let me know.

 

Icing internally happens when you have moisture mixed in with the refrigerant. As the refrigerant passes through the expansion valve and cools down, the moisture forms ice crystals that can block the passages. The other form of icing is when the evaporator gets too cold and ice forms on the coils externally, blocking airflow.

You most likely will need a new dryer (the silver can near the alternator) and to have to system vacuumed correctly to remove all traces of moisture before re-charging.