Poor AC performance. (1 Viewer)

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Nov 1, 2010
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I know this subject has been discussed many times before, but I couldn't find any discussion on my particular AC system, which has a cool box.

Well, my LC is a 2003 4.2TD with front AC + cool box... no rear AC.

The compressor clutch engages, and the AC works OK most of the time, but AC stops cooling as soon as the fan inside the cool box starts running.... so I can either have AC or cool box, but not both simultaneously. Furthermore, AC performance sucks on hot days. I tend to think that there might be some kind of valve stuck or the freon circuit might be clogged somewhere.

Is there any valve that controls freon flow to either the AC evaporator or the cool box evaporator, or am I facing some other problem here ?

I think I have enough freon gas, otherwise the clutch would not engage, but never actually checked pressures.

TIA.
 
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Jeddah
Yes you should have two thermal expansion valves (TXV's) one for the front evaporator and one for the cool box you should check both to make sure they work properly
 
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I know this subject has been discussed many times before, but I couldn't find any discussion on my particular AC system, which has a cool box.

Well, my LC is a 2003 4.2TD with front AC + cool box... no rear AC.

The compressor clutch engages, and the AC works OK most of the time, but AC stops cooling as soon as the fan inside the cool box starts running.... so I can either have AC or cool box, but not both simultaneously. Furthermore, AC performance sucks on hot days. I tend to think that there might be some kind of valve stuck or the freon circuit might be clogged somewhere.

Is there any valve that controls freon flow to either the AC evaporator or the cool box evaporator, or am I facing some other problem here ?

I think I have enough freon gas, otherwise the clutch would not engage, but never actually checked pressures.

TIA.
Yes there is a TEV for every evaporator as previously mentioned, check this out Thermal expansion valve - Wikipedia

Unless you have the correct charge in the system then you will just be chasing you tail.

But what do I know, I've only had 40 years in the A/C industry, every days a school day :)👍
 
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Yes there ia a TEV for every evaporator as previously mentioned, check this out Thermal expansion valve - Wikipedia

Unless you have the correct charge in the system then you will just be chasing you tail.

But what do I know, I've only had 40 years in the A/C industry, every days a school day :)👍

@Smiles Hey just for curiosity...when you say correct charge in the system...you mean correct amount of Freon gas that your AC system needs...??? so first ensure you have correct amount of freon gas in the system and then check the TEV and other components?
 
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@Smiles Hey just for curiosity...when you say correct charge in the system...you mean correct amount of Freon gas that your AC system needs...??? so first ensure you have correct amount of freon gas in the system and then check the TEV and other components?
Yes, nothing will work right without the correct weight of 134a, just because the compressor clutch kicks in doesn't mean that the pressures are correct, and the clue in TEV is the word thermostatic, so without the correct pressure temperature relationship because of insufficient (or even to much) refrigerant, the 'thermostatic expansion valve' can not open and close properly.

The procedure for recovering, pressure testing and refilling most A/C systems is not as straightforward as buying a refrigerant top up can from your local shop, unless want to do a botchjob.

The correct procedure can be found all over the interweb, or if you want a proper job done my best advice would be to go to a reputable auto A/C repair specialist.
 
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Yes you should have two thermal expansion valves (TXV's) one for the front evaporator and one for the cool box you should check both to make sure they work properly

Unless you have the correct charge in the system then you will just be chasing you tail.


Thank you guys,

I don't have any service manual covering my actual AC+cool box system, but looking at the EPC drawings, I can see that there is also a solenoid operated valve that regular AC systems don't have. It's part number 88690-60230 and I think it electrically enables freon flow to the cool box.

s-l1600.jpg



Yes, nothing will work right without the correct weight of 134a, just because the compressor clutch kicks in doesn't mean that the pressures are correct, and the clue in TEV is the word thermostatic, so without the correct pressure temperature relationship because of insufficient (or even to much) refrigerant, the 'thermostatic expansion valve' can not open and close properly.

Sounds logical !


Well I removed the front grill and looked at the sight glass and I can see heavy bubbling all the time, so I think I just might be low on freon. I thought the pressure switch was sensitive enough to disable the clutch below nominal operating pressure... but I it seems not to be the case and actually has a wide operation margin.

I think the AC has never been serviced, so the freon charge is the factory one... it has only 17 years :D
 
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Jeddah
Sight glass bubbles is not accurate you should check both high and low pressures and compare them to the chart against the ambient temp.
 
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While waiting for a couple of R134A cans to arrive next week, I decided to remove the horns and intercooler for cleaning, and I noticed that the AC condenser needs some cleaning too.

Is there any way to clean it without removing it ?.... maybe removing just the engine radiator does the trick of exposing the rear face of the condenser so I can wash it from there.... I wouldn't like open the freon circuit.
 

flintknapper

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While waiting for a couple of R134A cans to arrive next week, I decided to remove the horns and intercooler for cleaning, and I noticed that the AC condenser needs some cleaning too.

Is there any way to clean it without removing it ?.... maybe removing just the engine radiator does the trick of exposing the rear face of the condenser so I can wash it from there.... I wouldn't like open the freon circuit.


^^^^
That would be fine. As long as you have access to the front and rear of it so you can thoroughly clean it.....will work perfectly. No need for it to be removed from the vehicle.
 
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Well, R134a arrived today, and I checked pressures. Both low and high reading were below nominal (10psi and 150psi), so I added R134a until pressures reached "nominal values". Just added some 250 grams or so (total charge is 850 grams nominal for front AC + Cool box)

The closer I could get to nominal was about 15-20psi low side and ~250psi high side at 2000 RPM and 36°C ambient temperature (97°F). AC throws noticeably cooler air now and sight glass shows foamy/milky flow, just like before. Never could get the glass to show clear, except when AC is off.

The FSM states nominal 22-36psi low side and 200-220psi high side at 30-35°C and 2000RPM but this is for the V8 gasoline engine. My 100 has the 4.2 TD engine and I guess RPM for pressure testing will be lower... Don´t really know.



Any comments will be appreciated,
TIA-
 
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