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AC problem

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Mark Parks

Member
Joined
Nov 28, 2008
Messages
533
I had my 86 GN evacuated and had 134A installed. It blows cold BUT recycles continously. I changed the recycle switch but no help.Any ideas??
 
cycling usually means low refigerant. what's the low side pressure at 2k rpm?

I think I read once that it's normal for our systems to cycle, but I wouldn't be comfortable with constant cycling.
also if it's cool out and your condensor/fan are efficient, you increase the likelyhood of cycling.
 
its a ccot system cycling clutch orifice tube its supposed to cycle but anything thats bothering you is probally to fast. low charge is # 1 culprit but, could have a restriction somwhere usually at orifice tube or reciever drier. if 2 much oil was added this can cause a restriction in the orifice tube. also it could be over charged and triping the high pressure switch. very hard to diag without pressure readings. without pressure readings your basicly just guessing
 
compressor replacement

what is the normal charge to replace the a/c compressor and flush the system and re charge with 134??
 
its a ccot system cycling clutch orifice tube its supposed to cycle but anything thats bothering you is probally to fast. low charge is # 1 culprit but, could have a restriction somwhere usually at orifice tube or reciever drier. if 2 much oil was added this can cause a restriction in the orifice tube. also it could be over charged and triping the high pressure switch. very hard to diag without pressure readings. without pressure readings your basicly just guessing

If there is a blockage would the ac blow cold? Yesterday was a cool day but it blew 40 at the vent. On the plug that goes to the switch,
I can put a pair of needle nose pliers to complete the circuit and the compressor runs fine.It just won't recycle.
 
first of all i don't know what you mean by recycle. 2nd yes a restriction can still let the a/c blow cold thats what an orifice tube is its a restriction, but if to much oil or foreign debris is in the orifice tube it will cause a greater restriction can still blow some what cold but can cause low side pressures to get 2 low. you need to know your pressures if you don't we can not diag the system we can guess all day but without pressures or even temps we know nothing. are any of the lines icing up while system is runing
 
You don't use the same amount of 134 as you do r12. I think you only use like %90 of the specified amount of r12.

ex:3.25lbs (the amount specified for r12) x.9= 2.925 lbs r134a
 
first of all i don't know what you mean by recycle. 2nd yes a restriction can still let the a/c blow cold thats what an orifice tube is its a restriction, but if to much oil or foreign debris is in the orifice tube it will cause a greater restriction can still blow some what cold but can cause low side pressures to get 2 low. you need to know your pressures if you don't we can not diag the system we can guess all day but without pressures or even temps we know nothing. are any of the lines icing up while system is runing

What should the high/low readings be?
 
ok the low side if you have the r12 factory cycling switch (one on the drier accumulator) shoud cycle the clutch off at somewhere between 21 and 24 psi and on at around 44 psi. on the other hand if your overcharged the high pressure switch (sensor on discharge line of compressor right by compressor) i believe will kick compressor off around 280 psi. if your lost and want a complete explanation of how our ac sys works let me know i will try to explain as simple and short as i can. sorry for slow reply working nights this week
 
also wanted to add without knowing your pressures and ambient temps hard to diag system. somtimes in cold ambients compressor will cycle a lot more than inwarmer areas. ambient temps have a lot to do with the pressure readings too so they can vary somewhat.
 
You don't use the same amount of 134 as you do r12. I think you only use like %90 of the specified amount of r12.

ex:3.25lbs (the amount specified for r12) x.9= 2.925 lbs r134a

False. You charge it to the recommend PT values for R-134a with a gauge.
 
ok the low side if you have the r12 factory cycling switch (one on the drier accumulator) shoud cycle the clutch off at somewhere between 21 and 24 psi and on at around 44 psi. on the other hand if your overcharged the high pressure switch (sensor on discharge line of compressor right by compressor) i believe will kick compressor off around 280 psi. if your lost and want a complete explanation of how our ac sys works let me know i will try to explain as simple and short as i can. sorry for slow reply working nights this week

The compressor comes on goes off about every second!!! For me it has to be
SIMPLE!!!!!!!!!!!!!
 
im sure it is simple but without knowing the pressure you don't know if its an overcharge undercharge or a blockage. when you run it does any of the lines after the evaporator ice up quickly?? does your accumulator drier ice up?
 
im sure it is simple but without knowing the pressure you don't know if its an overcharge undercharge or a blockage. when you run it does any of the lines after the evaporator ice up quickly?? does your accumulator drier ice up?

NO icing
 
you said that you had jumped the cycling switch on the drier. and the sys stayed runnnig . did you notice anything icing up then?
 
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