1999 Acura TL Compressor Does Not Engage.

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1999 Acura TL Compressor Does Not Engage.

Postby stimbiton » Fri May 06, 2016 2:26 am

Hello guys.

1999 Acura TL

Here is whats happening:

- Static Pressure 90PSI. (more than enough to engage low pressure switch)
- Fuses Good
- Relays Good (tested continuity of coil, applied power(clicks), switched with different relay).
- If I jumper the the compressor at the relay socket, it turns on and works fine.

Here's what I found:

- Magnetic Clutch Relay Socket: Control side Multi-meter readings are 12-13V on one socket and 5 Volt on the Other socket.

The way I see it, is when the ac button is pushed, the Climate Control Unit should provide Ground on "5 Volt" socket so the relay can energize the coil and Pull the switch down to route 12VDC to Compressor Clutch.

The Issue is that Relay Coil, Fails to energize for some reason. This is the part that i dont know. Why is there 5 Volts on the socket? Is it the Controller? I shook the harness, where i could get to and readings did not change.

Any suggestions would be appreciated
Thank you.
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Re: 1999 Acura TL Compressor Does Not Engage.

Postby stimbiton » Fri May 06, 2016 2:30 am

- No Check Engine Light.

Can a thermostat still be an issue if there is no check engine light?
Can a low pressure switch be an issue?
Can ambient air sensor be an issue?

Thanks.
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Re: 1999 Acura TL Compressor Does Not Engage.

Postby Tom Greenleaf » Fri May 06, 2016 6:51 am

No harm and in fact suggested to get codes anyway. Many will be in wait long before a check engine light, symbol or whatever illuminates and most scanners will not read them all so may need higher end stuff.

Still, with a '99 you may just have a clutch air gap that's excessive. Check it. Same basics apply for that. It would all kick on with static that high (normal for the ambient temp) and click on with a tap on outer hub but might not re-engage as it's not strong enough for a couple reasons.

1. Air gap excessive. Possible when over .030 especially when warm/hot clutch as it isn't as magnetic* as when cold. Most like to be .020 some less or more but close to that.....

2. Careful jumping anything even for '99. 5v suggests a signal is probably to computer controls to either add the battery voltage via 5v signal to operate items by either adding ground or positive voltage. Beware.

Know about clutch coil's ability and magnetic* power both temp sensitive and voltage sensitive. When some first start you have it cold but less voltage for a short while and when running operating voltage but warmer.

* Magnetic power: Understand that all the relays (most) and clutch coils are electro magnets temperature and voltage sensitive. Add to that battery power when not running is a couple volts lower than when running and couple lower than that just while starter is cranking.

It matters mostly at clutch but does for relays as well. Believe me about that or find out yourself getting a paper clip glowing hot and try to pick it up with a magnet - it wont! Might wreck a magnet so AYOR with that,

T
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Re: 1999 Acura TL Compressor Does Not Engage.

Postby Cusser » Fri May 06, 2016 3:07 pm

Forgive me but I am a little confused.

1. Are you actually getting 12 volts positive AT THE COMPRESSOR itself, or just at some relay? With compressor clutch wire unplugged, can you measure the resistance in ohms of the AC clutch magnetic coil?

2. Does your blower fan work at ALL speeds? Some vehicles of this era have blower resistor modules that must be OK for the AC compressor to engage.
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Re: 1999 Acura TL Compressor Does Not Engage.

Postby stimbiton » Fri May 06, 2016 10:39 pm

Cusser wrote:Forgive me but I am a little confused.

1. Are you actually getting 12 volts positive AT THE COMPRESSOR itself, or just at some relay? With compressor clutch wire unplugged, can you measure the resistance in ohms of the AC clutch magnetic coil?

2. Does your blower fan work at ALL speeds? Some vehicles of this era have blower resistor modules that must be OK for the AC compressor to engage.


1. I am not getting 12 Volts at the Compressor because the Relay does not energize. Coil reads 3.2 Ohms.
2. Blower fan works in all speeds.

Tom I will get the built in DTC Codes as soon as I get my hands on it and i will get back to you with what I have found.

Thank you.
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Re: 1999 Acura TL Compressor Does Not Engage.

Postby stimbiton » Fri May 06, 2016 10:41 pm

Tom Greenleaf wrote:1. Air gap excessive. Possible when over .030 especially when warm/hot clutch as it isn't as magnetic* as when cold. Most like to be .020 some less or more but close to that.....T


1. Air gap is fine 0.016
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Re: 1999 Acura TL Compressor Does Not Engage.

Postby Tom Greenleaf » Sat May 07, 2016 7:32 am

Nice air gap, OHMs about right too. Staying concise, Tom
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