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99 Mitsubishi Montero Sport cooling problem

BIG on Sat May 17, 2008 11:38 PM User is offline

Year: 99
Make: Mitsubishi
Model: Montero Sport
Engine Size: 3.0
Refrigerant Type: R134A
Ambient Temp: 85
Pressure Low: 10-15
Pressure High: 185
Country of Origin: United States

I've owned my 99 Montero Sport for 3 years, the a/c has always worked well until the end of last summer and it seemed like is wasn't cooling as well. I did nothing about it until now. I hooked gages up today and it reads 40psi on the low side, 180 on high side, a/c on recirc, fan on high, windows down. The suction line is cool, pressure line is warm, compressor continually running with car idleing. I decided to add a little freon. When I opened the suction vavle to add the freon the suction pressure pegs the gage and the freon can never gets cool like it typically has on others cars in the past when I've added freon. But now the compressor started cycling and plunges to 10-15 psi pretty quick after the compressor comes on (in 2 seconds or so) and the high side won't read over 205-210. Still, my vent temps don't seem much cooler. My suction line seems colder at time (but doesn't seem consistently cold as it should) and the pressure line might be a little warmer. What's going on here? I've never seen a car act this way. Do I need more freon or have I overfilled? Do I need to get a thermometer in the duct to tell you what my vent temps are specifically for you to give me an answer? I'm confused but always had luck on others cars in the past. I need help or suggestions.

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

Chick on Sat May 17, 2008 11:59 PM User is offlineView users profile

How is your fan clutch? And yes, it's possible you overcharged it. I would recover what is in there, pull a deep vacuum and recharge the factory amount back in. Then it will either cool fine, or you'll be able to properly trouble shoot the system, knowing the full charge in is in it..Hope this helps...


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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

TRB on Sun May 18, 2008 12:53 AM User is offlineView users profile

As Chick has suggested, knowing what you have in the system is the best starting point.



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Edited: Sun May 18, 2008 at 12:17 PM by TRB

BIG on Sun May 18, 2008 9:09 AM User is offline

If I did overcharge my system, will it damage it to run it a few days as such until I get an opportunity to get it corrected? What happen with it overcharged?

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

TRB on Sun May 18, 2008 12:18 PM User is offlineView users profile

How long would you want your heart to run with high blood pressure? Sure it will work but it's not good for it!

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

BIG on Sun May 18, 2008 10:41 PM User is offline

I get your point but from my 205psi reading at 85 ambient, I wouldn't consider my high side too high so am I overcharged at all? But, I did check my vent temps late today with about 75 ambient temp and they won't get below 48... Not good.

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

BIG on Mon May 19, 2008 1:08 PM User is offline

I just looked in my Mitsubishi manual on CD to this 99 Montero Sport and it shows at 77 ambient the following should occur:

Discharge air = 41.0-44.6
high side = 145-189 psi
low side = 15-30 psi

My numbers at 85 ambient aren't far from this so I'm puzzled. My low side will drop to 10-12psi real fast when the compressor comes on and this is a little lower than shown above. But my 48 vent temps aren't nearly getting it done and I know they used to be better than this as the a/c cooled much better in the past. My high side isn't too high at 205psi with 85 ambient so surely my compressor is still good internally. Do I likely have a blockage somewhere (filter clogged) causing my low side to drop so fast when the compressor comes on or is this normal?

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

TRB on Mon May 19, 2008 4:35 PM User is offlineView users profile

Make sure you are not getting hot water in the heater core.

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

BIG on Tue May 20, 2008 7:56 AM User is offline



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

BIG on Tue May 20, 2008 7:58 AM User is offline

Interesting Tim... How in the world is the best way for me to check this? I've never thought of it or experienced it and I'm not sure how to best check this out. Thanks for any information.

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

BIG on Sat June 07, 2008 8:47 AM User is offline

To check and make sure I'm not getting hot water in my heater core I guess I can remove my glove compartment and feel around the heater coils. Aren't they usually down close to the evaporator coils in such a way that a common fan blows across both of them? Also, I really feel I need to recover all my freon, pull a deep vacuum then refill to assure I have the proper amount in the system. Problem is, I don't have a way to recover. Is there a method I can use to recover? I plan on buying a vacuum pump from this site, should I get the cheapest model that will pull the 25 micron vacuum just as a casual use homeowner? Also, when the system is discharged, will I lose oil and need to put oil back in the system? If so, how will I know how much I've lost? Thanks for all your help. My wife really wants this A/C fixed since it's hot here now and it's just not cooling well.

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

TRB on Sat June 07, 2008 11:09 AM User is offlineView users profile

Take two vive grip pliers and crimp off the heater lines running to the core. Run the a/c and if the temps look undo the vice grips. If the temps go up you know you're getting hot water in the core.

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

BIG on Sun June 08, 2008 11:52 PM User is offline

I put vice grips on both heater hoses. It had no effect at all. A/C will still only provide 48 degree vent temp at best. It was 93-95 degrees here today with about 80+% humidity. I don't know what to do next except evacuate my system and recharge to be sure I have the proper amount of freon. I plan on buying a vacuum pump off this site but I don't have a recovery machine. Why would I see the normal looking high pressure side readings (means my compressor is good correct?) but see this very fast drop on the low side to 12-15 psi when the compressor comes on? Do I have a restriction maybe? Does this Montero Sport have a filter in the system that could be clogged that I should change? What vacuum pump do you recommend for a infrequent user such as myself?

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

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