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  #1  
Old 07-01-2012, 12:13 PM
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need help with my a/c

i've searched, but i don't know exactly what i'm looking for.

i took my car to a highly recommended independent shop to get my a/c repaired. they said it was leaking, replaced the seals and gave me a full charge of r12. i picked it up friday right before a huge storm came through and knocked out everyone's (except mine, thankfully) power. the air was blowing very cold, and my pregnant wife was very thankful as we sat in the parking lot of her work waiting for the storm to pass.
however, saturday was a completely different story. the ac no longer blows cold, in fact there is no difference between the economy setting and either of the a/c settings. i went back to the shop this morning, but they do not have power and is closed. i will have to at least try to fix this on my own. i wouldn't be stretched for time if we weren't leaving for the tarheel state on tuesday. with projected highs 100+ a/c will be necessary.

i request that all advice is given as though to a child for i am completely ignorant of the nomenclature in an a/c system and how the a/c actually works.

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  #2  
Old 07-01-2012, 12:46 PM
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do you have gauges?
I would need pressures to know if the system is broken, or out of freon.
check behind the driver's headlight, there is a round bottle with lines and wires on it.
that's the receiver dryer. make sure both switches have wires connected to them.
open the fusebox, check to see if any fuses are blown.
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
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  #3  
Old 07-01-2012, 12:47 PM
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the 85 has RPM sensor, air gap senser, the klima relay, pressure and temp switches. all have to work in order for the a/c to be cold.
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
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  #4  
Old 07-01-2012, 01:44 PM
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i don't have any gauges, but i checked the dryer, and both electrical lines were connected and no fuses blown.
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  #5  
Old 07-01-2012, 02:42 PM
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lets make the assumption that the system is not broken, and there is enough freon in the system. what would keep the compressor from coming on? how do i know if the klima relay is bad? i took it out and re-seated it, same with the wires going into the receiver dryer.

i can spin the face of the compressor when the engine is off, but it does not engage when the a/c buttons are pressed. (i assume the face should spin with the speed of the belt if the compressor is working)
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  #6  
Old 07-01-2012, 03:01 PM
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Well, if you jumper the pressure cut off switch (on the receiver/dryer vstech mentioned) and everything else is working, the compressor should engage. Of course you just want to bump it because running the compressor with no pressure is very bad. But if jumping the switch engages the compressor, you pressure is probably low.

If you jumper the wrong 2 wires your aux fan in front of the radiator will come on - it's the other wires.
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Old 07-01-2012, 03:19 PM
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  #8  
Old 07-01-2012, 04:00 PM
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do you have a link, or directions, on how to jumper the cutoff switch?

i don't see how it could be low, the shop replaced the seals at the compressor hose fitting and added two pounds of r12.
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  #9  
Old 07-01-2012, 04:03 PM
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you just get a piece of wire (preferably with the blade style connector on both ends) and plug it into the two leads coming off the switch (edit: not the leads connected to the switch itself, but the two leads that go off into the guts of the car...). Any bit of wire should be fine for this if it reasonably thick. When you unplug the switch you will see the blade style connectors I am talking about. They sell them at Radio Shack or any hardware store.
Of course if no one can turn on the lights or a cash register....you may have to get creative.
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Current Mercedes
1979 maple yellow 240D 4-speed


Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT
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  #10  
Old 07-01-2012, 04:12 PM
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yeah i don't have anything that would work so i just stuck them together.
and wouldn't you know it, my compressor kicked on.
i did it twice because the sound was so unfamiliar.
so now what?.. could i have a bad switch or could have they missed a leaky seal (they did a vacuum test if that is relevant)
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  #11  
Old 07-01-2012, 04:24 PM
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More likely that you have low refrigerant than a bad switch. Now you need those guages VStech mentioned. Even if you can just get a cheapo one at the McParts store for the low pressure side (blue cap you can see with the hood open), you should see pressure above 0 without the compressor on. If you do, bad switch - if it is lower than 20-30 (IIRC) you still have a leak.

There are lots of threads here about how vaccuum testing for a leak is inadequate. The pressure is going to be reversed when the AC is on, so a leak may be hidden by suction and revealed by pressure the other way - if that makes sense. Better to pressurize the system (with dry nitrogen).

My money is on a leak that was not repaired.

IMHO you should plug your switch back in and suffer the heat until the shop reopens and let them complete the job they started.
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Current Mercedes
1979 maple yellow 240D 4-speed


Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT
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  #12  
Old 07-01-2012, 04:40 PM
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i guess i'll have to request that they do a pressure test. if they don't or can't do one, does anyone know of a good a/c shop in columbus, oh?
i feel like i just wasted $350 and vented 2 pounds of r12 into the atmosphere. (isn't that bad for more than just my wallet?)
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  #13  
Old 07-01-2012, 04:54 PM
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Quote:
Originally Posted by ohio diesel fan View Post
i guess i'll have to request that they do a pressure test. if they don't or can't do one, does anyone know of a good a/c shop in columbus, oh?
i feel like i just wasted $350 and vented 2 pounds of r12 into the atmosphere. (isn't that bad for more than just my wallet?)
Yes, that is why it would be wise to take it back to the same shop as they would most likely fix it for no or little charge. Of course that assumes they are a reputable place. And of course they need to be open which is your problem.
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  #14  
Old 07-01-2012, 05:52 PM
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  #15  
Old 07-01-2012, 07:06 PM
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
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