Need AC help

[Hank857]

Ok we have been trying to track down what is wrong with the ac on 90 TT. Was able to get under and the clutch is not engaging, does not even click when turned on. Everything else works, high idle kicks in, blower motor works, temp gauges for AC work, all fuses have been checked inside care and under hood. Even took relay from AC and changed with one from sub-fan (?) and still nothing. Checked pressure for the 134 and it was OK, a little high.

So can anyone offer a thought on where to go now? I cannot locate the wires at the clutch so just where are they connected? Pretty much stumped but am no AC guys by any stretch.

Thanks Hank

[marty1mc]

Probably low on Freon which means you have a leak somewhere. Has it been converted to R134A?

[McShanks]

If pressure is a little high, that shouldn't be the issue. I know the clutch won't turn on if pressure is low... I recently did the conversion and initially had the same issue because my gage was not reading pressure properly. I had to get a new gage, and found out pressure was low. There is a sensor in the circuit that will not allow the compressor to run if refrigerant pressure is low.

[Hank857]

Thanks that is also what we found, the gauge 1st used was bad and gave false readings. Still gotta see if we can change the front seal as it is apparently leaking. Can this be changed without evacuating the system or is this something for a ac shop?

Yes it has been converted to 134.

[marty1mc]

If you are talking about the front seal on the compressor, probably not. Also, you need to evacuate the system anytime you open it. Also, you probably will need a new receiver/dryer unit as well. If the system is opened for an extended period of time, that will absorb too much moisture (that's it's job in the AC system).

But, you can rent an evacuator fairly cheaply. It's pretty easy to use. I would recommend a good set of gauges, both hi and low so you can SEE what the system is doing. R134a only takes 80% of the charge of an R12 system when converted.

I would suggest that you first check to see if there is pressure in the system. Try and relieve some pressure from the low side (easiest to get to). If there is positive pressure and you get R134 coming out, then just try putting in a can, see if the compressor turns on. The system capacity is about 1.7lbs, so it doesn't take a whole lot. Also, try to find R134A with dye. It will allow you to look at each connection and see where it leaks. All you need is a black light and darkness. I would be willing to bet, though, your leak will be in the expansion box. The orings in there go through a huge expansion and tend to wear out. You can easily see this if you use dye. You can pull out the motor resistor from the expansion box and shine the black light in there. You will likely see a bright yellow on the right side low on the expansion core. That is where the orings, tube and the core all meet.

Good luck.

[McShanks]

Yeah, marty is right on. Did you do a full conversion or a walmart conversion? If you didn't do the whole set of orings and seals, you might wanna do that now since you are gonna have to open the system anyway. R-134a uses different oil than R-12 and may degrade the o-rings and seals causing a loss of pressure. http://www.carpartsdiscount.com/auto/pa ... 3593=94596

And if you are REALLY ambitious, and it regularly gets above 85/90 degrees where you live, spend the $100-$150 on a parallel flow condenser. I want to do that myself. My AC takes a long time to get cold on really hot days because the old serpentine flow condenser does not give off enough heat for 134a. The 134a needs more surface area to give off heat and work more efficiently, so if you can swing it, this is highly recommended. http://www.supremecondensers.com/nissan ... ensers.php

The above links are the first examples I could find. Do some more diggin for a better price. Hope this helps!

Good luck!

P.S. I hope you don't have to replace your condenser... Ones I saw were over $300... But you gotta do whatcha gotta do eh...

[es.biggs]

Don't you need MACS Section 609 Cert. to operate AC recovery equipment?

[Hank857]

thanks, we got it to work, went for a drive and when we returned it started to leak fluid from the front seal on the compressor, so he will need to take to someone for repair. Will talk to a local shop tomorrow maybe.

Its my sons car, he just got it so would guess it is a shop conversion to 134.

Thanks again.

[NolimitZ32]

Don't you need MACS Section 609 Cert. to operate AC recovery equipment?

From what i understand if 134 is involved and not R12 than no cert is needed.

[stewartmotorsport]

That is correct - you do not need a cert for R134 - although they still get pissy if you vent it into the atmosphere.

Although it turned out that he was indeed low on refrigerant, compressors will also not kick on if the pressure is too high. This usually indicates that the system is plugged up somewhere. Often times, the compressor will "vent" excess pressure as a fail safe. Scared the stink right out of me first time I heard that.

When that happens, you have to open the system, find the source of the clog (orifice tube, etc), remove the tube, put that section of pipe back together, flush the whole system with a cleaner, follow that with shop air - LOTS OF air - replace the orifice tube (or whatever your car uses) with a new one, replace the drier, replace the compressor, evacuate the system, inject oil, start car, and start filling with refrigerant.

Ask me how come I know so much about A/C all of a sudden? lol