ac not working when car is at a stop
#1
10-30-2009 | 12:06 PM
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Posts: 22
ac not working when car is at a stop
I have a 1999 saturn sl2 with 47000 miles. A few weeks ago the ac stopped cooling when at a stop. When moving the ac cools just fine. Also the car gets hot. I tested the harness to the fan and when the car is running there is 14 volts. With the key in the acc position there is no voltage. With this this test I am assuming that the fan motor is bad. If there is power to the harness then is it safe to say that the relay and fuses are working? I tries to jump the fan motor directly to the battery, but where the connection is located I'm not sure if I got a good connection. Am I correct to start with replacing the fan motor? If not can someone help me with any suggestions of what else might be wrong. Thank you.
#2
10-30-2009 | 05:12 PM
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Joined: Jul 2005
Posts: 11,027
From: Slightly off center
aux cooling fan only receives voltage when
1) coolant is sufficiently hot (as determined by PCM via measurement of voltage drop across ECTS)
or
2) When A/C is engaged and fan switch is on
If aux fan is not spinning when A/C is engaged as described above AND you have verified voltage at the fan under these conditions, then indeed it sounds as though your aux cooling fan requires replacement.
Replacement should correct the "A/C hot while not moving" and "car getting hot" issues as well.
1) coolant is sufficiently hot (as determined by PCM via measurement of voltage drop across ECTS)
or
2) When A/C is engaged and fan switch is on
If aux fan is not spinning when A/C is engaged as described above AND you have verified voltage at the fan under these conditions, then indeed it sounds as though your aux cooling fan requires replacement.
Replacement should correct the "A/C hot while not moving" and "car getting hot" issues as well.
#4
10-30-2009 | 08:13 PM
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Joined: Jul 2005
Posts: 11,027
From: Slightly off center
COULD BE bad -- check resistance across ECTS by removing connector (squeeze to remove).
Should be a couple hundred ohms at operating temperature and a few thousand ohms when cold (search the site for exact resistances).
if you have never replaced ECTS you will likely want to replace with brass tipped oem style replacement (original was a resin tipped sensor which is prone to cracking and failure). Replace connector too (dealer only part)
____
Note: With A/C off, the aux cooling fan should kick in by about 3/4 tick on the temp gauge. however, if fan itself is defective, this won't occur. You could put your meter on the fan motor and look for the 14v to show up across the motor at the 3/4 tick mark, but with a likely defective aux fan, you run the risk of overheating.....so I don't recommend testing it this way
Should be a couple hundred ohms at operating temperature and a few thousand ohms when cold (search the site for exact resistances).
if you have never replaced ECTS you will likely want to replace with brass tipped oem style replacement (original was a resin tipped sensor which is prone to cracking and failure). Replace connector too (dealer only part)
____
Note: With A/C off, the aux cooling fan should kick in by about 3/4 tick on the temp gauge. however, if fan itself is defective, this won't occur. You could put your meter on the fan motor and look for the 14v to show up across the motor at the 3/4 tick mark, but with a likely defective aux fan, you run the risk of overheating.....so I don't recommend testing it this way
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