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DStarr
Dodge Dakota
JOIN HERE
7/13/2004
15:33:47
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 Subject: A/C r134a pressure
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Message:
Anyone konw what the pressure on the gauge should be on a R134a A/C on a 2000 Dakota?
Thanks,
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GraphiteDak
GenIII
 
7/14/2004
02:23:03
| RE: A/C r134a pressure
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Message:
Depends on ambient temp, how clean the coil is, fan speed, etc.
They vary on cars pretty bad. On small reachins, refers, etc the 134a stuff never goes over say 250. But I see it go way higher in cars all of the time.
You should WEIGH in the charge (count cans from empty) but if just topping off you can go by looking at your suction side pressure and see where the saturation point on your gauge. Use a clamp on thermometer on the suction line coming FROM your evaporator. The temp should be only a few degrees above your sat point on your gauges. The suction line should be COOL. 40 degrees or so. With som many variables in car A/C's it's hard to say and car A/C's isn't my everyday buss.
It must be summer time, cuz this is the 3rd topic this week for A/C I've seen.
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Lab Rat
GenIII
7/14/2004
11:29:52
| RE: A/C r134a pressure
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Message:
Another method for CCOT type systems is to charge it until the evap inlet and outlet are the same temp. This is an age old filed method that is actually very accurate. Check it before you charge it:
Evap inlet colder than outlet = undercharged.
Evap inlet same as outlet = optimum charge.
Evap ooutlet colder than inlet = overcharged.
Also, confirm fan operation, clean and comb the condenser fins.
Lastly, the 2000s did not have the hybrid electric fan in addition to the viscous fan if I'm remebering correctly. The addition of one makes a world of difference, especially at idle.
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FloriDak
Dodge Dakota
JOIN HERE
7/15/2004
15:01:05
| RE: A/C r134a pressure
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Message:
I think the pressure on the low side (the cold pipe) should be either 42 or 44psi max... forgot which. You can get an inexpensive gauge at Wal-Mart. Those things help a lot and also tell you the correct pressure. You should also fill the 134a up on the low pressure side.
Filling up on the high side (the hot pipe) will damage things.
It is also safer to fill the system slower by keeping the can upright. Turning the can upside down dumps liquid right in and could fill it too fast. You might be able to get away with dumping liquid right in, but taking a few extra minutes to charge the system is less risky and works just fine.
Just make sure to have the engine idling and have the A/C compressor turned on when you're filling the gas and measuring pressure.
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FloriDak
Dodge Dakota
JOIN HERE
7/16/2004
09:47:03
|  RE: A/C r134a pressure
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Message:
almost forgot...
It is good before you hook up the gauges and fill hoses to the truck to turn on the gas and let freon run all through the hoses for a little bit.
This gets the air out of the hose and helps keep air from building up in the system.
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