PDA

View Full Version : A/c system diagnosing...



BuRHan90SC
07-29-2009, 02:29 AM
hello guys i m back again...lol my car is finally running super and since i have changed the fuel pump to 255lph i have felt faster top end i duno could be my imaginations anyways....

now i have to fix my A/C...first..wen i push the max AC button on my manual climate control it does nothing but blow hot air and fans doesn't come on if i push the AC button...so my question is if i m low on freon and switch on the dryer doesn't let my compressor engage so would it stop the fans to come on too? like every car i have seen have fans turned on with AC no matter wat i m sure same with SC but how about my situation?....and how can i find out if i m low on freon without machine...any electrical places to check on for possible problem?....give me everything for AC system on this car as i dont have any manual to look at to diagnose...all i have is u guys to rely on lol....Thanks in advance..:)...oh and its VERY HOT here, SC cooks me everyday as u guys know how hot these cars getS....its almost like 95F here everyday.....I need my AC to work....thanks again :D

slowpoke
07-29-2009, 04:28 AM
check the codes, if there is a problem with signal getting to the compressor there will be a code. otherwise get a cheepo gauge from auto zone or advanced auto. the cheepo's read i think about 34-42 for a charged system. if your low make sure to put in 1.5oz pag oil per 12oz of coolant. also use the sealer type if you still have some left, if the system is fully purged then replace all the seals. once you have it charged dont forget to use leak detector all over the entire system to make sure your not leaking anywhere. also if your system is still on r12 then this would be a perfect time to replace all the seals and convert it to r134. good luck and keep you cool:cool:

BuRHan90SC
07-29-2009, 06:16 AM
check the codes, if there is a problem with signal getting to the compressor there will be a code. otherwise get a cheepo gauge from auto zone or advanced auto. the cheepo's read i think about 34-42 for a charged system. if your low make sure to put in 1.5oz pag oil per 12oz of coolant. also use the sealer type if you still have some left, if the system is fully purged then replace all the seals. once you have it charged dont forget to use leak detector all over the entire system to make sure your not leaking anywhere. also if your system is still on r12 then this would be a perfect time to replace all the seals and convert it to r134. good luck and keep you cool:cool:

sorry i forgot to mention that it has been converted to r134...say i m low on freon how do i put it in without machine:o....and there seems to be no code i checked last time when it wasn't working but the connector on the compressor i would is very lose it just comes off i tightened it and compressor still does not engage...any electrical places to look after or check or test before i go all over on ''Mechanical A/C system''..?

slowpoke
07-29-2009, 02:45 PM
the cheepo gauges they have at (autozone, advanced auto, napa, ext ) are hooked up to a small can of coolant. you do not require a machine to fill the systems. that machine is for industrial non-stop use and recovery of coolant because of the myth of global wraming/ice age/ the government wants to tax us to death. napa is the cheapest yet advanced auto has the best gauges. there is a low side port on the passenger side that you will hook your hose to. it will only connect to one of the 2 fittings so you cant mess it up. they made it army proof. make sure your while filling that you have the car on and the a/c set to max. if the compressor kicks on but your fan does not then stop and get the fan going before you continue. if you look in the kitchen supply area at you grocery store you'll see some small cooking thermometers. get one of those to put in you vent while doing this. once your systems is charged you should have at the highest 65 coming out of your vents. this temp will get colder when you drive. idle is always the warmest the system will run. alot of systems this old lose there dust caps. make sure you have dust caps on the high and low side valves once your done. they help preserve the valves

BuRHan90SC
07-29-2009, 04:12 PM
ok thank you i will do that and report back:D

BuRHan90SC
07-29-2009, 08:29 PM
how many volts i suppose to be getting at the connector which is on the top of the compressor...i m getting none....is that could be the problem compressor not engaging? and wat could cause the volts to stop coming there, any fuse for AC system ? thanks:)

Duffy Floyd
07-29-2009, 08:35 PM
My SWAG would be that the pressure switch on the accumulator dryer is defective OR there is not enough freon. You could jumper the switch contacts in order to "force" the compressor to engage and then use the gages to determine the state of the charge. If it were me I would have the gages hooked up first to minimize the time the compressor turns with a potentially low fron charge.

What year SC? Assuming a 90 from your user name.

XR7 Dave
07-29-2009, 08:47 PM
1) The EEC does not monitor the AC so there will never be any codes.

2) R134 will typically always leak in an R12 system due to the small molecular size of the refrigerant. It will leak out of your compressor seals and everywhere else, not to mention its hard on the compressor and not very efficient. I do not recommend R134 for an R12 system. Instead use Duracool. It will seal your system, is compatible with all systems, and will cool much better. To install Duracool you'll need to first draw down the system of any prior refrigerants. Be sure to follow instructions for charging the system with Duracool.

3) You can force the compressor to come on by jumpering the pressure switch at the dryer. You can do this to verify that the circuit works, but don't leave it jumpered while driving as that will overwork the compressor and can cause excessive head pressure in the system. Of course if it's empty, that won't happen, but still don't leave the compressor hot wired like that. With the switch jumpered (and of course the AC on and car running), the compressor should run and the fan should come on automatically. If there is any refrigerant in the system it should start to generate cold air (and if you have a gauge on it, pressure should fall to around 30-40psi. If it goes lower than 25psi then the system is low on charge. Chances are it's basically empty, but you could also be suffering from a bad pressure switch. This test will determine if you have a sufficient charge in the system.

4) If it is a bad switch they are available everywhere and are easily replaced.

BuRHan90SC
07-29-2009, 09:19 PM
i jumped the pressure switch at the dryer and compressor came on with the fans:D but i don't get cool air..its still blowing HOT air...so now i am sure that its VERY low freon..rite?..anyone has specs to test pressure switch so just to find out if its gud? i m pretty sure that after jumping the switch i m getting HOT air so it means that the pressure switch could be working gud but its jus triggering cuz i m low on freon...?:)

brandywine11297
07-29-2009, 11:42 PM
if the refrigerant is low, then the compressor will not come. you are correct.
i say just retro fit it to 134a. i have been running 134a for over a year now with no problems.

BuRHan90SC
07-30-2009, 12:29 AM
if the refrigerant is low, then the compressor will not come. you are correct.
i say just retro fit it to 134a. i have been running 134a for over a year now with no problems.

i think u havnt read the above posts we made:p

XR7 Dave
07-30-2009, 08:22 AM
It's pretty obvious that the system is empty of freon, but the only way to verify is to put a gauge on it.