I have a leak somewhere in my AC system. I have a 1996 Honda Accord - I refilled it about 10 days ago with 24 oz of r-134a after I vacuumed the system to -10psi for about 20 minutes.

The system "filled" with no problem. I ended up with 17 psi on the low side and about 80'ish psi on the high side. AC was working pretty well after that.

Now, 10 days later, I have no AC again. I hooked up my gauge to the high and low side and found that my low side was still at 17 psi, but my high side was also at 17 psi (see attached picture). This was while the car was running and the AC running, too.

I obviously have a leak... but can someone tell me if they can tell where the problem might lie with these symptoms? I injected UV dye into the system but have yet to locate the source of the leak.

Any help is greatly appreciated...

 

Your original pressures should not have produced cooling. Since they did, the gauge readings are questionable. Were both gauges connected and hose shut-off valves opened w/ service valves closed?

A pressure of 17 psi on low and high side means the system is near empty. Under these conditions, the compressor should not run. Did you check whether compressor clutch was engaged or not when these pressures were taken? Was engine running? Compressor should have been disabled by the AC pressure switch which would not close at 17psi.

Suggest having a leak test performed by a shop, or recharge w/ UV-dyed refrigerant and lube. You need some added lube w/ this much refrigerant loss, as lube is carried out of leak by refrigerant.

Leaks under the hood can usually be spotted visually. Look for oily/dirty/greasy accumulation around hose crimps, connections, compressor clutch rotation plane, fittings, and condensor face. W/ UV Dye they are easier to spot w/ a good UV light.

If everything under the hood is dry, you must have a large evaporator/expansion valve leak. This is located in the evaporator housing under the dash.

Post back further information for help.

good luck

 

I understand what you're saying about the PSI - I may be stating it wrong. If you look at the attached photo, the high-side PSI was around +80 on the outer (black) scale... maybe that's not a measurement of PSI. It would equate to about 350 psi on the inner (also black) scale. If that's how you're supposed to read it, then the low side was 60psi? If you look at the photo you'll know what I'm talking about.

I did inject UV dye into the system, but no leak seemed apparent. I need to seriously clean the engine bay to get rid of every little white speck of junk so i can more easily identify the UV dye under my black light.

That being said, the equal pressure from both high and low sides might indicate a compressor problem?

 

If both sides have equal pressure, then the compressor is not doing anything.

See if the clutch plate on the a/c compressor is engaging with the a/c pulley and spinning when the engine is running and you turn on the a/c. Do both fans on the radiator turn on when the a/c is turned on?

 

Those photos are not readable, at least I can't read them. I will look at my gauges and tray to make some sense of them.

good luck

 

Looking at those gauges and my own, I suspect that pressures was 60-70 psi on both high side and low side gauges. Can't be sure because size is too small. If compressor was not engaged this makes some sense, but does suggest that system is low on refrigerant.

good luck

 

Hi Tex, since this thread is dealing with what I wanted to know, I won't make a new one. I would like to know what normal working pressures of the high and low side should be when one is finished charging the system with freon. I have looked in my manual from top to bottom, searched this forum also with no answer to be found. My manual just says to fill it to the refrigerant capacity which is like 22.9 oz. But I think that is from an evacuated state. I have a very slow leak in my 1997 Honda Accord 2.2 V-Tec and would just for now, like to top the charge off to its capacity, but I need to know at what pressure to stop charging. I have done a lot of reading about this and I THINK this would be sufficient until I have the funds to get all of this done correctly, (fix leak, then evacuate etc...).

Thanks

 

There is no exact or accurate method of charging by system pressures. Following is what I have found from other sites and by experience.

High side should be ~ 2.5*Ambient Air Temp(degF) entering condensor in psig and low side should be cycling between ~25-45 psi. For example ambient air is 90F, then high side would be 225 psig.

This is charging in the shade, max AC, Max Fan, doors and windows closed, and stabilized system for 10 mins. Cabin air should be well cooled. Engine rpm should be 1500-2000 rpm steady. If it is really hot out it may be difficult to reach low side conditions. In that case I look for cool-down (Air temp on Floorboard-Air Temp fron center vent) to be 35-45 degrees. If high humidity, it will be towards the lower end of that range.

Add charge very slowly (perhaps 20-30 secs of charging, then stop and allow to stabilize) through low side only watching system pressures. Don't overcharge! This is approximate, not rocket science.

Freon is R12, R134a is called Suva by Dow. You should be using R134a.

When system leaks, some lubricant is lost. Continued "top-offs" can result in compressor failure due to lack of lubricant. At some point lubricant should be added.

Suggest reading an Auto AC Manual (Haynes, MasterCool) to understand basics of using a manifold set to charge.

good luck

 

Very good information. Thanks very much for your reply. Will do on the Haynes.

Joel

 

Also consider your gauges are no good. I bought a A/C manifold gauge set from Harbor Freight and I couldn't get a good reading from high side. Complete junk in my opinion.