Automotive Air Conditioning Information Forum (Archives)

toydiesel on Sat June 07, 2014 3:36 AM

Year: 1996
Make: Toyota
Model: Land Cruiser
Engine Size: 4.5
Refrigerant Type: R134a

After driving for about 30 mins on freeway, the high side pressure is getting higher and higher during idling. After about 2 mins of idling, the pressure got so high that it had the compressor shut off. The system has new compressor, expansion valve, and drier. Evaporator and condenser were flushed. Any ideas on what could be causing this?

Dougflas on Sat June 07, 2014 7:40 AM

reduced airflow across condenser. Make sure fan if electrical is working. If machanicalfan clutch, most likely fan clutch can be failing.

Cussboy on Sat June 07, 2014 8:09 AM

Thinkin' same.

HECAT on Sat June 07, 2014 9:08 AM

Yup, not removing enough heat from the condenser at idle, thus the pressure rise. Mist water on condenser and see pressure drop to verify.

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toydiesel on Sat June 07, 2014 1:22 PM

Thanks for the replies. Fan clutch was rebuilt with thicker fluid. I can feel the airflow when I put my hand in front of the condenser area. I forgot to mention a shorter drier was used, about 2" shorter. The short drier is made for compact car. Will a shorter drier have higher flow restriction or cause problem like this?

Dougflas on Sat June 07, 2014 2:50 PM

Quote
Originally posted by: toydiesel
Thanks for the replies. Fan clutch was rebuilt with thicker fluid. I can feel the airflow when I put my hand in front of the condenser area. I forgot to mention a shorter drier was used, about 2" shorter. The short drier is made for compact car. Will a shorter drier have higher flow restriction or cause problem like this?


Probably not. Do the water hose thing. Many fan clutches work fine for cooling radiarors but do not work for AC condensers. If the water misting drops pressures radically, that is the area of your problem.

toydiesel on Mon June 09, 2014 5:43 PM

Water misting dropped the pressures a lot and made the AC much colder too. Will a new condenser address the problem? The condenser looks clean visually, no debris or bugs on it. Is there any chemical to clean the fins effectively?

Jag987 on Tue June 10, 2014 2:05 AM

Nope, a new condense will not help. It is an airflow issue across the condenser. The heat is not being removed. Make sure the fan shroud is in place. After that, it is time for a new fan clutch. Yes, I saw that the clutch was just rebuild with thicker fluid, but is it working? It might be enough to keep the engine cool, but not enough for the AC. I have never dealt with a rebuilt fan clutch, but do not like the idea of it.

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I bought a can of 134a at w**-mart that had a stop leak, oil, and dye in it. It also had a hose and a gauge, so now I'm an AC pro!

toydiesel on Tue June 10, 2014 3:33 AM

Quote
Originally posted by: Jag987
Nope, a new condense will not help. It is an airflow issue across the condenser. The heat is not being removed. Make sure the fan shroud is in place. After that, it is time for a new fan clutch. Yes, I saw that the clutch was just rebuild with thicker fluid, but is it working? It might be enough to keep the engine cool, but not enough for the AC. I have never dealt with a rebuilt fan clutch, but do not like the idea of it.

Fan shroud is in place. A new fan clutch is going to pull less air than the current clutch. I don't see how it is going to solve the problem.

TRB on Tue June 10, 2014 1:59 PM

Unless you have dead spots (plugged passages) in your condenser, a replacement will do very little. Removal of the heat load is what is needed. This is done in two ways, larger parallel flow condenser or more air flow across the condenser.

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mk378 on Tue June 10, 2014 5:03 PM

Like TRB said, condenser could be clogged with debris from the old compressor. When replacing a compressor that suffered internal mechanical failure, also replacing the condenser is highly recommended.

Overcharging with oil or refrigerant impairs condenser performance. Flush solvent that wasn't fully removed will also hinder heat transfer.

Edited: Tue June 10, 2014 at 5:06 PM by mk378

bohica2xo on Wed June 11, 2014 2:54 AM

OEM condensor for this vehicle is a Serpentine unit.

It is very easy to plug a passage in a serpentine unit, and lose performance. Even with 50% of the passages plugged with debris, they still flow well enough to make you think they are clear.

With all of the parallel passages they are very difficult to flush as well. A replacement condensor is a $137 item from the site sponsor:
1996 Land Cruiser Condensor

A new accumulator is another 11 bucks. I would replace both, and flush the evaporator & lines back to clean & dry. Drain any oil from the compressor,and start with the proper oil charge for the vehicle.

The system is 18 years old. It may have had a failed compressor replaced, or several oil charges added. Since the condensor is the primary filter in this system, it should be replaced.

B

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