Weird AC Problem (S13 w/ S13 SR20DET) - Ac Keeps shutting off/on during driving. - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

opponheimer · 07-21-2008, 01:53 PM

My AC light (the green light) keeps shutting off and on at an interval of about 4 seconds during driving or cruising. At idle the AC stays on constantly. The car runs shitty as hell because of it.

The AC system shouldn't be over pressurized. When I wired the AC i spliced the blue/green ac wire form the s13 sr20det harness into the stock s13 chassis harness.

Anyways, could someone provide me a list of things to check for?

Thank you!

Z U L8R · 07-21-2008, 08:44 PM

the light is coming on and off because your compressor is turning on and off. it's cycling fast for a reason. it's either low on freon because you have a leak, but since it isn't cycling at idle i'm thinking your hi side pressure is building up (which they do) when you're at driving rpm's and either your expansion valve is bad (which is very common on 240's) or your condensor fan's not working (i can't see your car in front of me). or your system is overpressurized......

without your car in front of me to check anything i'm leaning more towards the expansion valve being bad than anything but something in your favor......to check all of this all you have to do is see if your condensor fans work, and hook up some guages to your hi and low sides and see wtf is going on. let the car run at operating temp while you're watching the guages with the compressor on. then hold the rev to 1500-2000rpm and see what the pressure's are doing, this time of year it should read some where around 35-45psi on the low side and 175-195 (depending on your ambient temperature where you are) on the hi side with the fan on full blast @ 1500rpm

my advice to you is don't guess,

hook some guages up to it and see wtf is really going on, then diagnose the problem once you have more specific information to work with.

gl
Dave

opponheimer · 07-21-2008, 09:01 PM

Z: this is what i just wasted the last 4 hours of my life on:

So I hook a gauge to my LP port, at idle, the pressure is at 40psig and every time i rev the car up it dips to 35psi, if i rev it a little higher, the compressor will shutoff until the rpms drop again.

So i added a little freon and it got worse, so i figured OK over-pressurized -time to bleed a little refrig., hard to tell how much.

Anyways, somewhere along the line i removed then reinstalled the AC relay and i dont know if it is f*cked up or waht, but the ac will not come on at on anymore.

I tried bleeding some pressure from the LP side to depressurize the line, but I don't think I let out enough, but I dont know if I fixed anything because I'm not sure if the damn relay is messed up or not, because suddenly it decides not to work anymore. If I jump position of Relay Post #5 to #2, (Power constant to Compressor Power) the compressor of course comes on and AC works, but the pressure still reads high.

Should I stick withthe stock relay or hardwire my own? So now AC doesnt work at all. Fuckin hell..

Does s13 have a triple pressure switch?

SoSideways · 07-22-2008, 08:27 AM

I'm sure S13s do.

Get yourself a copy of the proper year range FSM.

Sileighty_85 · 07-22-2008, 08:40 AM

Mine did the same thing before it was the Thermo Contol Amp (Solder Points broke for the plug)
fixed it but then my Expansion valve stuck open -o- so no more cold air

Compressor was working fine but no cold air

I checked my pressure with a gauge read 25psi
but as i added freon the compressor would turn on and off
on for 1-2 seconds then shut off for 1+ min or so
but when i reclaimed it back to 25ish it would kick on

Turn out I had a bad gauge and over pressureized the system and blew the relief valve on the compressor -o-

boostin13b · 07-23-2008, 06:05 AM

You really need to know what your high side pressure is as well. It sounds like your low side was ok pressure wise. You have a pressure switch that will shut off you A/C if the pressure is too low or too high, I believe it will shut off when it reaches around 400psi on the high side. By reading both pressures, you will know if there is a blockage somewhere, Your dryer could be freezing up as well. An easy way to check that is run your A/C for a while and see if your dryer starts to build moisture on it, or even feel it, but be careful. The dryer should be hot or warm, not cold, if it's cold then you have a blockage.

07-21-2008, 01:53 PM	#1
opponheimer Zilvia FREAK! Join Date: Apr 2007 Location: Bikini Atoll Posts: 1,267 Trader Rating: (3) Feedback Score: 3 reviews	Weird AC Problem (S13 w/ S13 SR20DET) - Ac Keeps shutting off/on during driving. My AC light (the green light) keeps shutting off and on at an interval of about 4 seconds during driving or cruising. At idle the AC stays on constantly. The car runs shitty as hell because of it. The AC system shouldn't be over pressurized. When I wired the AC i spliced the blue/green ac wire form the s13 sr20det harness into the stock s13 chassis harness. Anyways, could someone provide me a list of things to check for? Thank you!

07-21-2008, 08:44 PM	#2
Z U L8R Zilvia FREAK! Join Date: Jan 2007 Location: Georgia Age: 43 Posts: 1,194 Trader Rating: (0) Feedback Score: 0 reviews	the light is coming on and off because your compressor is turning on and off. it's cycling fast for a reason. it's either low on freon because you have a leak, but since it isn't cycling at idle i'm thinking your hi side pressure is building up (which they do) when you're at driving rpm's and either your expansion valve is bad (which is very common on 240's) or your condensor fan's not working (i can't see your car in front of me). or your system is overpressurized...... without your car in front of me to check anything i'm leaning more towards the expansion valve being bad than anything but something in your favor......to check all of this all you have to do is see if your condensor fans work, and hook up some guages to your hi and low sides and see wtf is going on. let the car run at operating temp while you're watching the guages with the compressor on. then hold the rev to 1500-2000rpm and see what the pressure's are doing, this time of year it should read some where around 35-45psi on the low side and 175-195 (depending on your ambient temperature where you are) on the hi side with the fan on full blast @ 1500rpm my advice to you is don't guess, hook some guages up to it and see wtf is really going on, then diagnose the problem once you have more specific information to work with. gl Dave __________________ RB25 280z GT30/76R 441hp/381tq 11.9@125

07-21-2008, 09:01 PM	#3
opponheimer Zilvia FREAK! Join Date: Apr 2007 Location: Bikini Atoll Posts: 1,267 Trader Rating: (3) Feedback Score: 3 reviews	Z: this is what i just wasted the last 4 hours of my life on: So I hook a gauge to my LP port, at idle, the pressure is at 40psig and every time i rev the car up it dips to 35psi, if i rev it a little higher, the compressor will shutoff until the rpms drop again. So i added a little freon and it got worse, so i figured OK over-pressurized -time to bleed a little refrig., hard to tell how much. Anyways, somewhere along the line i removed then reinstalled the AC relay and i dont know if it is f*cked up or waht, but the ac will not come on at on anymore. I tried bleeding some pressure from the LP side to depressurize the line, but I don't think I let out enough, but I dont know if I fixed anything because I'm not sure if the damn relay is messed up or not, because suddenly it decides not to work anymore. If I jump position of Relay Post #5 to #2, (Power constant to Compressor Power) the compressor of course comes on and AC works, but the pressure still reads high. Should I stick withthe stock relay or hardwire my own? So now AC doesnt work at all. Fuckin hell.. Does s13 have a triple pressure switch?

07-22-2008, 08:27 AM	#4
SoSideways Post Whore! Join Date: Apr 2003 Location: 你老母 Posts: 4,371 Trader Rating: (4) Feedback Score: 4 reviews	I'm sure S13s do. Get yourself a copy of the proper year range FSM.

07-22-2008, 08:40 AM	#5
Sileighty_85 Post Whore! Join Date: Dec 2006 Location: Misawa, Japan Posts: 6,815 Trader Rating: (8) Feedback Score: 8 reviews	Mine did the same thing before it was the Thermo Contol Amp (Solder Points broke for the plug) fixed it but then my Expansion valve stuck open -o- so no more cold air Compressor was working fine but no cold air I checked my pressure with a gauge read 25psi but as i added freon the compressor would turn on and off on for 1-2 seconds then shut off for 1+ min or so but when i reclaimed it back to 25ish it would kick on Turn out I had a bad gauge and over pressureized the system and blew the relief valve on the compressor -o- __________________ 後輪駆動車１番 1989 Built SR GT2871R -363whp 1998 S14 W/RB25- 250ish (For Now) 1986 SR86 - 200ish 1990 R32 GTR - 320hp Don't Buy Engines from JDM-Online http://zilvia.net/f/businesses/207457-jdm-online.html Don't Buy XS-Power or SSAC Shit

07-23-2008, 06:05 AM	#6
boostin13b Leaky Injector Join Date: Feb 2004 Location: Tampa Posts: 123 Trader Rating: (0) Feedback Score: 0 reviews	You really need to know what your high side pressure is as well. It sounds like your low side was ok pressure wise. You have a pressure switch that will shut off you A/C if the pressure is too low or too high, I believe it will shut off when it reaches around 400psi on the high side. By reading both pressures, you will know if there is a blockage somewhere, Your dryer could be freezing up as well. An easy way to check that is run your A/C for a while and see if your dryer starts to build moisture on it, or even feel it, but be careful. The dryer should be hot or warm, not cold, if it's cold then you have a blockage.