I broke the A/C on a 99 Civic LX
10-26-2013
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I broke the A/C on a 99 Civic LX
First of all, i'd like to say that when I'm working on cars, I don't make very smart decisions, so please go easy on my lack of common sense.
Well, my AC wasn't t blowing quite as cold as it used to, so I went and got a can of r134a and pulled out my plastic manifold. I hooked it up and started the car. I noticed that the compressor was turning off every 15 seconds or so, and I thought it would charge faster if it remained on, so I grabbed a paper clip and put it in to the compressor relay socket , but, being the genius I am, I put the paper clip into the wrong two holes. I saw a spark and ever since then, the only way to get the compressor to activate is to jump the relay.
Now I THINK I checked the right fuses, which all seem to be working fine. So, I would appreciate it very much if somebody could explain to me what I broke and how to fix it.
Well, my AC wasn't t blowing quite as cold as it used to, so I went and got a can of r134a and pulled out my plastic manifold. I hooked it up and started the car. I noticed that the compressor was turning off every 15 seconds or so, and I thought it would charge faster if it remained on, so I grabbed a paper clip and put it in to the compressor relay socket , but, being the genius I am, I put the paper clip into the wrong two holes. I saw a spark and ever since then, the only way to get the compressor to activate is to jump the relay.
Now I THINK I checked the right fuses, which all seem to be working fine. So, I would appreciate it very much if somebody could explain to me what I broke and how to fix it.
10-26-2013
#2
If you think a good mechanic is expensive, try hiring a bad one
Re: I broke the A/C on a 99 Civic LX
Engine compartment fusebox, fuse #56, 20A
Dash fusebox, fuse #17, 7.5A
Dash fusebox, fuse #17, 7.5A
10-26-2013
#4
If you think a good mechanic is expensive, try hiring a bad one
Re: I broke the A/C on a 99 Civic LX
Got a voltmeter? And do you know how to use it?
Generic relay socket.
Probing with a meter, engine running, ac on, you should see 2 terminals with 12v battery+ voltage, and 2 terminals with ground.
Terminals 1 and 2 should show power and ground when tested with a voltmeter, key on. One comes from a fuse, the other goes to the clutch field coil. (doesn't really matter which has what, just that both are present. Same for the other terminals below)
On 3 and 4, one should show battery power (key on) from the dash fusebox, and the other is a switched ground that comes from the PCM.
The PCM only supplies that ground when the AC compressor is supposed to be turned on.
The HVAC system must make a valid request to the PCM, then the PCM must choose to allow the AC clutch request to be enabled. The PCM can stop the compressor relay from turning on under various conditions, such as overheating or wide-open throttle operation.
A scantool that can give live engine data can tell you if the AC clutch request is made to the PCM, and can tell if the PCM is (or thinks it is) engaging the clutch relay.
If you shorted the PCM terminal to a power source, you could have smoked the PCM.
Generic relay socket.
Probing with a meter, engine running, ac on, you should see 2 terminals with 12v battery+ voltage, and 2 terminals with ground.
Terminals 1 and 2 should show power and ground when tested with a voltmeter, key on. One comes from a fuse, the other goes to the clutch field coil. (doesn't really matter which has what, just that both are present. Same for the other terminals below)
On 3 and 4, one should show battery power (key on) from the dash fusebox, and the other is a switched ground that comes from the PCM.
The PCM only supplies that ground when the AC compressor is supposed to be turned on.
The HVAC system must make a valid request to the PCM, then the PCM must choose to allow the AC clutch request to be enabled. The PCM can stop the compressor relay from turning on under various conditions, such as overheating or wide-open throttle operation.
A scantool that can give live engine data can tell you if the AC clutch request is made to the PCM, and can tell if the PCM is (or thinks it is) engaging the clutch relay.
If you shorted the PCM terminal to a power source, you could have smoked the PCM.
10-26-2013
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I do have a voltmeter, but I'm not entirely sure how to use it. I set it to 9v and put one lead in to terminal 1 and the second into terminal 2, and did the same for the other two. Both times there was a reading. Is that good?
10-26-2013
#6
If you think a good mechanic is expensive, try hiring a bad one
Re: I broke the A/C on a 99 Civic LX
I set it to 9v
If you have your meter set on 9v and you test the 12v battery, what reading do you get?
put one lead in to terminal 1 and the second into terminal 2, and did the same for the other two. Both times there was a reading. Is that good?
What was the reading?
10-26-2013
#7
If you think a good mechanic is expensive, try hiring a bad one
Re: I broke the A/C on a 99 Civic LX
If you can, use a light bulb to see if the PCM can supply sufficient ground to operate a small load (the relay). (terminals 3 and 4)
Bend down the wires on the end of a #194 bulb (license light) to use as a test light, stick this in the terminals, then run the engine and AC to see if the light illuminates.
Bend down the wires on the end of a #194 bulb (license light) to use as a test light, stick this in the terminals, then run the engine and AC to see if the light illuminates.
10-26-2013
#9
If you think a good mechanic is expensive, try hiring a bad one
Re: I broke the A/C on a 99 Civic LX
terminals 3 and 4 read 9.1.
Lets check individual terminals now.
Do this:
engine running
AC ON
Meter black lead attached to the negative battery post.
Measure volts with the red meter lead at terminal 3 and then at 4. What are the two readings?
Now move the red meter lead to the positive battery post,
Take the black meter lead and repeat the above checks on terminals 3 and 4.
What are the two readings now?
10-26-2013
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Sorry about the wait, I had to make a grocery run.
So, with the positive lead on the battery:
Terminal 3: 9.15
Terminal 4: .22
And negative on the battery :
3: 5
4: 13.8
So, with the positive lead on the battery:
Terminal 3: 9.15
Terminal 4: .22
And negative on the battery :
3: 5
4: 13.8
10-26-2013
#11
If you think a good mechanic is expensive, try hiring a bad one
Re: I broke the A/C on a 99 Civic LX
So terminal 3 is a problem as I see it here.
If you had the engine running and AC turned on at the time of the checks, it appears that
You only have a partial ground circuit from the PCM to the relay.
This indicates to me that it probably toasted the output driver (output transistor can't handle more than about 1 amp load) for that relay control circuit inside the PCM.
I assume you stuck your paper clip between terminals 3 and 4?
If you had the engine running and AC turned on at the time of the checks, it appears that
You only have a partial ground circuit from the PCM to the relay.
This indicates to me that it probably toasted the output driver (output transistor can't handle more than about 1 amp load) for that relay control circuit inside the PCM.
I put the paper clip into the wrong two holes. I saw a spark and ever since then,
10-26-2013
#13
If you think a good mechanic is expensive, try hiring a bad one
Re: I broke the A/C on a 99 Civic LX
I guess the next question will be what to do about it....
New, used, or send it in for repair?
New, used, or send it in for repair?
10-26-2013
#15
If you think a good mechanic is expensive, try hiring a bad one
Re: I broke the A/C on a 99 Civic LX
You are on your own now.
New, dealer. Online is probably cheaper.
Used, junkyard. car-part.com
Rebuild yours? Inquire with parts stores, many have programs where they send your computer in and get it repaired.
I wonder if aftermarket has these PCMs available?
Once you get it done, it should be plug and play.
No key programming since yours doesn't use immobilizer.
Kids, let this be a lesson: Paper clips are terrorist weapons!
New, dealer. Online is probably cheaper.
Used, junkyard. car-part.com
Rebuild yours? Inquire with parts stores, many have programs where they send your computer in and get it repaired.
I wonder if aftermarket has these PCMs available?
Once you get it done, it should be plug and play.
No key programming since yours doesn't use immobilizer.
Kids, let this be a lesson: Paper clips are terrorist weapons!
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