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looks good works bad

rweston on Mon July 27, 2009 9:05 PM User is offline

Year: 1995
Make: toyota
Model: tacoma
Engine Size: 2.7
Refrigerant Type: 134a
Ambient Temp: 92
Pressure Low: 51
Pressure High: 272
Country of Origin: United States

The Toyota just doesn't cool much at all. refrigerant is full (maybe even a bit over full). pressures seem high to me. Outside air is 92, temp of the liquid line is 118 after evaporator and 139 before evaporator. temp of vapor return line is 89. Cool Air temp out of vent is 89.
Frustrated,I recovered 13 oz refrigerant out of system,( full system = 21oz). Now the temps are low side = 35 psi high side= 210 psi. Cool air temp out = 90 liquid line temp = 116 . sight glass turned white.
Just my feelings, it looks like not enough refrigerant is getting into evaporator core from the expansion valve.
Has anyone dealt with this model before? how is the best way to dig into the expansion valve. It doesn't look like there is any access from under the hood. Or maybe I have just not quite understood what is the problem!
refilled system with 7 of the 13 oz recovered. Sight glass is now clear, but temps are still the same as original, psi's are slightly lower.
thanks Rex

Chick on Mon July 27, 2009 9:19 PM User is offlineView users profile

first, the worst thing you can do is let refrigerant out, and put it in.. Should be weighed in. I would suggest you recover the refrigerant, recharge into a deep vacuum the factory amount listed on the underhood tag, then trouble shoot, but don't let any out.. Sight glass should clear if using R134a in a R134a system. But not all the time, so it's a tool but not always accurate, a lot depends on the temps for R134a sight glasses to clear.. Did you add anything else, like sealers, O ring lube etc?? a big No no in this business...

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

rweston on Mon July 27, 2009 9:43 PM User is offline

Its a used truck and I don't know the past history. Also, I did replace all the refrigerant that was recovered out of it along with the oil. no new added.

bohica2xo on Mon July 27, 2009 10:37 PM User is offline

You have a condensor issue.

A 21 degree drop across the condensor, and a high side pressure ratio of almost 3:1. That is crappy performance, especially for that vehicle.

You need to check the air side of the condensor carefully, and clean it well. If the performance is much better at highway speeds, your fan clutch is probably dead.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

rweston on Mon July 27, 2009 11:41 PM User is offline

I've got the refrigerant out and now it's vacuumed down to 26.5 We are at 4500 feet elevation so 26.5 is about all I can get. I'll let it sit over night.
I got 27 oz out of it. Some of it is oil.
As for the condenser, I'll clean it in the morning, but It wasn't very dirty, a few bugs and an occasional bent fin but not a lot of plugged up fins. I read a thread about fan clutches today. I'll look for problems with it.
thanks for all your help
Rex

Cussboy on Tue July 28, 2009 2:46 PM User is offline

I'm agreeing with bohica2xo.

rweston on Tue July 28, 2009 6:43 PM User is offline

The vacuum held good overnight. I reinstalled 21oz of the 26 oz removed. sight glass cleared at about 20 oz. the condenser is cleaned up and bent fins are straightened.
The fan clutch slipped when first started but after just a short time, it tightened up and pulls hard even at slow rpms. It seems to be ok.
today is 97 out doors. I took more care in reading the temps in and out of the condenser. Input = 154 output = 113 . vapor line out of evaporator is 94 / cool air temp is hardly modified at 90. Pressures are just as high as yesterday. liquid line high side= 281 / vapor low side 62.
If the compressor wasn't working well, I would expect the high side to be low instead of high and the low side to be high just as it is. I'm having a hard time understanding how the high side is so high and the low side high also. I was looking for the low side to be around 40 psi or lower.
I am also struggling with the fact that we have a lot of pressure on one side of the expansion valve but it doesn't seem like much refrigerant is getting into the evaporator. That is why i was concerned about getting to the expansion valve in the first place.
With these new stats, do you think you could get me going in the right direction?
Thanks Rex

TRB on Tue July 28, 2009 6:54 PM User is offlineView users profile

Compressor Type Nippondenso 10PA17 10-Cyl.

Compressor Oil Capacity (3) 4.8 ozs.
Refrigerant (R-134a) Capacity 19.4-22.9
System Operating Pressures
Low Side 22-37 psi (1.5-2.5 kg/cm2 )
High Side 205-235 psi (14-16 kg/cm2 )

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When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

bohica2xo on Tue July 28, 2009 7:23 PM User is offline

If those pressures are at idle, you have either a restricted condensor or an airflow problem. Since you have a serpentine condensor, there is a chance you have one or more blocked channels.

Spray some water on the condensor, and see if the high side drops like a rock.

Your low side is high because the refrigerant is hot. I doubt the TXV is the issue here. If the TXV was stuck closed, the low side would be high, but the high side would stabilize at a lower pressure - the refrigerant would be staying in the receiver.

A fan clutch that starts off slow is tired. A new unit will ROAR on a cold start. Tim has posted here before about a trick to lock up the Taco clutches.

A full load test will provide more data points. 1500 engine rpm, doors open, cabin fan on highest speed. Run for 5 minutes, record pressures & vent temp while running 1500 rpm.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

TRB on Tue July 28, 2009 7:28 PM User is offlineView users profile

Should not have to lock up the 95 clutch fan. I have this same truck with the V/6 4x4 extra cab and it's an ice box.

-------------------------

When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

bohica2xo on Tue July 28, 2009 8:22 PM User is offline

Well, that narrows it down some. If tim's truck is an "IceBox" with 125f ambients, your condensor is a door stop.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

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