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99 Mitsubishi Montero Sport gage reading help please?

BIG on Sat October 06, 2007 8:20 AM User is offline

Year: 99
Make: Mitsubishi
Model: Montero Sport
Engine Size: 3.0
Refrigerant Type: R134
Country of Origin: United States

I have a 99 Montero Sport with original factory air that has been gradually getting where it doesn't cool very well. I put a thermometer in the air duct and can only get down to 48-50 degree air. I have gages and have worked on several auto a/c systems in the past with the help of this site but I don't have a manual to this vehicle so I don't know what my gages should read to determine if I need R134 or not. Can any of you tell me what my high and low side numbers should look like so that when I put on my gages I know whether to add freon or not? Thanks for you help and any information.

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It takes all kinds of people in this world, just less of some than others.

Chick on Sat October 06, 2007 10:18 AM User is offlineView users profile

Pressures will vary with the ambient temp, better if you post the pressures along with the outside temp you took them at, that will help us help you..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

BIG on Sat October 06, 2007 10:40 AM User is offline

I just put gages on it this morning. Here are the numbers:

Outside air temp = 77F
High side press = 210-240psi
low side press = 21-24psi
humidity = 80-90% (very humid here in East Texas)
vent temp = 50-57

What do you think? Compressor sounds quiet and when I put the high side quick connect on green oily freon came out so if I need to add freon I shouldn't need to add any compressor oil with it should I

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It takes all kinds of people in this world, just less of some than others.

Chick on Sat October 06, 2007 10:56 AM User is offlineView users profile

does this truck have an electric fan or just the engine fan..Pressures look high for that ambient if fans are working. If they are, a recover/recharge with the system amount may be needed to confirm full charge.. If the fan(s) are not working properly, then you may be low and the airflow problem needs to be fixed first... Also, high humidity will affect cooling, let it idle in the shade on lower fan speed and see how much the vent temps drop..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

BIG on Sat October 06, 2007 12:55 PM User is offline

It has a mechanical engine fan that is working fine. Also has an electric "pusher" fan for the condensor and it works properly. The above numbers were taken with all windows down pulling fresh air in (not on recirc) on the 3rd (out of 4) fan speed. I just ran it again in the shade on low fan speed on recirc with all the windows up and the vent temps got down to 49-50F with outside air temp 84, humidity is still 80-90%. I didn't put the gages on it for this second "test" but will if it's necessary. I bought this vehicle 3 years ago with only 54k. It now has only 94k. The a/c has never had anything done to it and has always worked well until this past summer so I doubt it's overfilled? I did notice the evaporator is "peeing" but not as much as I think it should given the humidity level. It is VERY sticky, heavy air outside right now and the evaporator is only dripping one big drop every other second or so. Thanks for any help or information. I don't want to just assume it's low of freon and add it until you folks tell me that's the case.

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It takes all kinds of people in this world, just less of some than others.

Chick on Sat October 06, 2007 1:42 PM User is offlineView users profile

With the guages hooked up, spray a "MIST" of water on the condensrer, if the high side drops like a stone, you have air flow problems. ( a clutch fan can appear to be working, when it's worn) If the pressure drops slowly, it's OK.. I doubt that your low with those pressures, but one step at a time... Let us know what you find..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

BIG on Sat October 06, 2007 5:58 PM User is offline

I let it idle, windows down fan on next to high and misted water on the condensor. The high side went from 225- 150 real steady and fast - took about 5sec. The low side was on 32 and the vent temp was only 60F at the time. For the record, this Montero Sport engine temp gage runs dead in the middle and NEVER fluctuates. It can literally be 105F outside and 80% humidity and it never moves at all. Wouldn't this indicate I couldn't have a bad fan clutch? Also, the fan clutch feels like it has good tension but surely it's good or I would see some increased engine temps while stopped at red lights in this awful Texas heat. What should I suspect from here?

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It takes all kinds of people in this world, just less of some than others.

Chick on Sat October 06, 2007 6:01 PM User is offlineView users profile

Time for a new fan clutch..Then you may need to recover, vac/recharge the system to underhood sticker amount.. Your cooling will then return to acceptable temps.. When you have proper air flow and full charge, the high side will drop with misting water, but not by much, and not fast.. Hope this helps..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

BIG on Sat October 06, 2007 7:08 PM User is offline

I just drove to town and the vent temps will only get to 47F on recirc and med-high fan. I'm not questioning your knowledge but could my fan clutch be out causing this problem when this car will run cool even in this terribly hot, humid Texas heat? I mean, I just can't imagine if I have a bad fan clutch my engine will run cool in these conditions...

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It takes all kinds of people in this world, just less of some than others.

Chick on Sat October 06, 2007 7:40 PM User is offlineView users profile

I see two problems, low charge (masked by poor air flow) and a bad fan clutch. Once you have proper air flow, your pressures will drop showing a low charge. You can add R134a now if you like, by charging feeling the suction line. Should get very cold back to the compressor. Add a couple ounces at a time while monitoring vent temps and high side pressures. Just watch your high side pressures don't go above 2.5 to 3 times the ambient temp. You will get cooling again, but pressures will be high until the air flow problem is fixed.. Misting the condenser, and fast pressure drop is an indication of a "weak" fan clutch.. If it's more than three years old, or more than 50,000 to 75,000 miles, it's due for a change...Hope this helps.

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

BIG on Sun October 07, 2007 8:10 AM User is offline

Thanks for the help Chick. I only keep asking about the fan clutch because even driving down the highway at 70mph last night I can only get vent temps of 48F and surely I don't have an air flow problem at that speed even if I do have a "weak" fan clutch right? I mean, it seems to me I could literally take my fan/clutch assembly off my vehicle and as long as I'm moving down the rode at high speeds I should get enough air flow to eliminate any air flow problem right? But, on the other hand, with a weak fan clutch I'm obviously going to have air flow problems at very slow speeds and stopped at traffic signals. Also, what about my electric "pusher" fan in front of the condensor/radiator assembly? It does come on and work but could it be "weak" also? I just assume since it's electric and coming on that it's performing correctly, etc but is that necessarily the case? At idle you can put your hand 3-4 inches away from the front of the radiator and feel the suction real good. This air flow problem baffles me.

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It takes all kinds of people in this world, just less of some than others.

Chick on Sun October 07, 2007 6:43 PM User is offlineView users profile

You missed my point... You are underchared which is giving you poor vent temps, but the pressures are deciveing since you have poor airflow (makes pressures appear normal) .. If you were to tape the gauges to the windshild, you would see the pressures drop just like the water mist test.. You can check this way, recover the refrigerant, and recharge into a vacuum the "sticker" amount back into the vacuum, your pressures will be high, but it will cool much better on the highway Thenb you will see the fan clutch needs to be changed, and the ptressures will be "normal" and you'll have better cooling at all speeds.. It's a little tough with engine driven fans and pusher fans to just go by pressures. You really do need the proper amount of refrigerant in there and then do your diagnostic work.....One affects the other...

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

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