I am trying to recharge the ac system on my 89 iroc 305 engine . The fella I bought it from last summer told me his mechanic said it had a leak in the evaporator . I was counting on having to tear into that but before doing that I pulled a vacuum on it and was glad to see no leak over night . I then change the orifice tube and tried to charge the system but could just get enough refrigerant in to make the compressor cycle continuously on / off and then it would take no more refrigerant . Low pressure 80 to 100 plus and high pressure about the same .. I tore into it and cleaned all passages , lines etc . and proceeded to charge again but with same results . Thinking bad compressor , I change the compressor, dryer and orifice tube and cleaned again with same results . Now , after the third compressor it is the same only now I can get in just about 28 to 30 oz. of refrigerant in system with same high pressures on the low side and still about 100 on the high side and still cycling on / off continuously . Any thoughts ?

 

How often does it cycle? The system is design to kick the compressor off around 32 psi on the low side. There is a relationship between pressure and temperature at around 30 PSI your evaporator will fall below freezing and turn to a block of ice. Your symptoms sounds like the your system is not filled but it could also be a weak high pressure switch. The high pressure switch is just a safety switch. It could be by past while you have gages on it to fill the system. Also keep track of how much you put it. If it says 2.2 lbs then that is what you put in. Use a scale if needed.

 

Thanks Gorn , when I try to charge it will start to cycle on and off after just 6 or 8 oz of coolant it is a constant on/off . 3 to 4 seconds of each if that makes sense . I have a new compressor and high pressure switch and I am using a scale . Here is what I did yesterday . I took it all apart again , took the condenser out and did a good flush on it along with cleaning the coils out . I did not clean it good enough the first time . Did not take the evaporator out but did a better flush on it . The original orifice tube looked clean but I replaced with new ones two times and they were visibly clean each time but this time when I took it down this new tube was filthy so that says a lot to how well I did not clean the system . I am putting the condenser and radiator back in this morn and trying it again today . Will let you kn ow . Thanks again .

 

what are using to flush the system?

 

ac flush from o'reilly .

 

Do you recomend somethimg else ?

 

At this point you need to figure out what is cycling the compressor. It kind sound like you have a restriction in the high side. The "black" you saw would lead me to believe that as some point the dryer/accumulator failed and some of it is blocking a line or the condenser..

 

I have been using reman compressors but the parts house is bringing in a brand spanking new one today , for me . While at it , the dryer and orifice tube will be replaced also . Have flushed system again and ready for parts . Will let you know in a couple of days .Thanks again .

 

If it is still acting up after follow the high side tube with your hand. You are feeling for a cold or cooler spot. You can also slide your hand over the condenser. The cold stop would indicate blockage/restriction. Make sure you done you oil calculation base on the manual and the compressor manufactures instruction. You want to vacuum the system for at lease 2 hours.

GL
Gorn

 

I have been vacuuming for 1 hour . Will do the two hour thing this time . Everything I see says eight oz. of pag 150 with three oz. already in compressor . Lacking 5 more oz. , I will put an oz or so in the dryer and same for evaporator , lines and rest in compressor . After all is put together will then pull a vacuum . Sound right to you ? Thanks .