I am trying to diagnose the problem w/ my a/c.
All parts are original. The car has been without a/c for years.
I have injected dye & one can of r134 but found no leaks.
The compressor runs but cycles very infrequently & briefly.
The condenser fan has not come on.
The system just barely cools.
I'd like to know what my next steps should be.
Can I test the evaporator in the car or remove it for a pressure test?
A step by step diagnosis would help.

Thanks

 

Can't help with the evap testing but a few things to think about.

Cycles on and off, what are the high and low side pressures. This could be a sign of too much or not enough refrig.

You say the condensor fan does not come on. When the compressor does engage, both fans should come on. If there is enough pressure in the system for the compressor to "try" to run, turn the key on, turn the ac on - Do both fans run? This works on the 3rd (86-89) and 5th gens (95) I have, not sure about the 4th but knowing Honda...it should.

 

Both cooling fans should run w/ AC engaged. Missing fan will affect idle cooling but not cooling at any significant foward speed. It could be bad fan motor or fan relay. These cooling fan motors do wear out and most have been replaced at least once by this age vehicle.

As PM points out, you should borrow or buy (ebay) an inexpensive set of manifold gauges to see what's happening (too low or too high). Either case will cause the pressure switch to disable compressor in a cyclic manner as described.

I have read (no experience) that R12-R134a conversions of most Accords results in marginal cooling performance. Retrofitting a 94 Accord condensor may help (designed for R134a), but don't know how difficult that retrofit would be.

AC system likely has leaks in the evaporator. I had a 90 Accord that I repaired and found several of the oring seals in expansion valve-evaporator connections were leaking. They were distorted by dissimilar metal corrosion of aluminum/brass connections. Powder builds up and oring is distorted until leak occurs. It can be fixed w/ cleaning (very careful not to damage aluminum or brass fitting), oring lubricant (nylog), and reassembly. Note, I found this same leak pattern in both 90 Accord and 94 Accord when I rebuilt AC systems (after problems).

Evaporator removal is not difficult in these cars. It can not be tested in place w/o special fittings. You can test in place for leaks w/ a refrigerant sniffer, but finding them is tricky at best. It's probably more efficient to simply remove and have a shop test evaporator externally. Rebuild evaporator/expansion valve connections at this time.

Check compressor shaft seal for leaks by looking for an oily/dirty ring on parts around the compressor rotation plane. Oil slung out attracts dirt to form the ring. If this is present a compressor shaft seal or replacement compressor is necessary.

A new receiver/drier should have been installed w/ retrofit. If not, this component should be replaced. Old R12 dessicant bag may rupture and block system resulting in damage to compressor, expansion valve, etc.

good luck

 

Can the evaporator be tested by hooking up a vacuum pump to it after it is removed from the car?

Thanks

 

It can but you will have to purchase the fittings to blind one expansion valve fitting and connect vacuum pump to the other. An AC shop will have these fittings or perhaps may do the test for you. I think they use "plumber's plug" fittings to seal. A hydraulic hose supply shop may also be able to supply the fittings. If you obtain these fittings you can test the evaporator in place from engine side of firewall.

I have never tested an evaporator out of the car, but when entire AC system is reassembled, I perform a system vacuum test. Vacuum for 15 minutes, isolate w/ gauge set, and let is sit for 1/2 hr. It should hold w/ only a very small vacuum level drop (< 1-2" hg). If this test won't hold, no point in rechargring. Find the leak.

Rent or buy a decent vacuum pump. The venturi-effect vacuum generators are not adequate to pull enough vacuum to dry the system.

good luck

 

I tested the system with the mainfold gauges.
With the engine off: Low = 82 psi High = 120 psi
With the engine on: Low = 30-33 psi High = 225 - 245 psi Vent 58 degrees
(morning with/ car in the shade)
In the heat of the day the car barely cools.
The psi readings seem to be within the normal?
One line, I believe the discharge line from the condenser was very hot.
I have added about 2 - 12 oz. cans of R134 to the system.
I still can't find any leaks.
What do you suggest I do next?

Thanks

 

Either your gauges are badly calibrated or you didn't have one side or other open to the gauge. W/ gauges open to air (hoses removed) check that they zero out. W/ Engine OFF, the gauges should have same pressure or reasonably close (+/- 5 psi). Usually, the pressure (psi) will be fairly close to ambient air temp (degF) unless engine is fully warm, in which case pressure will be higher than air temp (degF). Check your gauges.

If gauges are off, the measurements can't be interpreted.

If you have not added replacement lubricant and simply added R134a, you will have a system failure. R134a will not transport the original lube (mineral oil) and compressor will sieze due to lack of lubrication.

Retrofitting requires more than simply changing refrigerants and adding fittings.

good luck

 

I checked the pressures again. (gauges were at zero before being connected)
Engine Off - LOW- 93 HIGH 95
Engine On - LOW 25 HIGH 185
The compessor does not cycle. It is always on.
I have not found any leaks.
The system cools, but can't keep up in the heat of day.

The system had been retro fitted years ago by a mechanic in order to charge & test it. Did he add oil? I'm not sure.

Thanks

 

Your low side pressure looks good, but high side may be low depending on ambient air temp when pressures were taken and rpm of engine.

Suggest the following conditions for testing charge level. Car in shade, engine at 1500-2000 rpm, max fan, recirculate. Add R134a to bring high side pressure up to ~ 2.3-2.5*ambient air temp (air entering condensor) degF. So at 90F high side would be about 207-225 psi. This is approximate and anything close should work OK.

Again, I've heard that retrofits for 90-93 Accords do not produce good cooling levels. I maintained my 90 Accord w/ R12 until I sold it. It cooled good, but not great, perhaps lowest temps would be 40F directly from upper center outlets w/ fully cooled interior (~ 75-80F on floorboard, pax side). This cooling is a "pulldown of ~40F. If you can achieve that, you should have acceptable cooling.

You may be able to allow a little refrigerant to escape and see if lubricant is carried. If it's PAG it has a distinctive chemical smell. If nothing is carried, you should be concerned.

good luck