A/C Issues

[Johnathan Nagel]

I have a 2001 Plymouth neon. Last year the ac worked great but the pulley was wasted so i pulled the relay to keep it from kicking on as well as taking the belt off. i then proceeded to have the system evacuated so i could replace the compressor as a clutch kit was gonna cost close to the same amount. Fast forward to about 2 weeks ago when i finally got the new compressor installed. the compressor will not cycle with the relay in, so i swapped it with a known good relay (horn). Horn still worked but still no ac. So i jumpered the relay spot and got the compressor to actually cycle on so i know the wiring from relay to compressor is good. i also know the compressor is good because it did blow cold. The issue is i cannot get it to cycle normally without jumpering the relay. Any thoughts?

Jumpering the low side switch does nothing either.

Topic

[Richard Kirshy]

From your description the load side of the relay is functional.
Have you tested the control side of it though?

[Johnathan Nagel]

Not quite sure how to do that, its probably worth mentioning that these cars the ac on off is pcm controlled via a high side switch on compressoor and low side switch on expanson block at firewall. Something is not telling the pcm to kick on the compressor. i should also mention that i cant get the high side connector to seat on the compressor, could that be the whole problem?

[Richard Kirshy]

[color=orange][i]Not quite sure how to do that, its probably worth mentioning that these cars the ac on off is pcm controlled via a high side switch on compressoor and low side switch on expanson block at firewall. Something is not telling the pcm to kick on the compressor.
[/i][/color]
This should help about the relay.

i should also mention that i cant get the high side connector to seat on the compressor, could that be the whole problem?
A good possibility…
Do you have the correct compressor for your vehicle?

[Johnathan Nagel]

Yeah I do, I managed to get that sensor plugged in finally still nothing not sure where to go from here at all, do you know if the pressures in the system being wonky will keep it from cycling at all, also I think I tested control side with ac “off” .2 with it “on” it jumps to like .6

[Richard Kirshy]

If there is little to no refrigerant in the system, it will not work.
As to testing the control side of the AC relay.
You’ll need a wiring diagram to sort through that.
But many high current relays are usually switched using higher voltage ( 5 – 12VDC )
or negative switched ( still being supply 5 – 12VDC

[Johnathan Nagel]

It’s just bothering me that there is no voltage supply to the pressure switches everything I’ve read says there should be

[Richard Kirshy]

Again ..
You will need a wiring diagram of the system in order to trouble shoot it.
Without that you’d just be guessing.

[Josh]

A wiring diagram you say? For the HVAC you say? Here ya go:

From Mitchell’s ProDemand service subscription used by my trade school.

You can roughly the same info from ALLDATA: http://www.alldatadiy.com/buy/

Costs $30USD/year for 1 car.

Also has the system been properly evacuated and recharged with the use of a refrigerant machine and not one of those DIY bottles sold at the local WalMart?

Attachments:

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[Johnathan Nagel]

Well I just checked the acsense wire at the pcm it has voltage, the low pressure cutout also has voltage but the low pressure cut out does not. Also shouldn’t the whole system cycle on and off if there isn’t enough refriggerant but it’s vacuumed down?

[Richard Kirshy]

If your pulling a vacuum on the system, it shouldn’t start.
The vacuum is what draws the refrigerant initially.
Once the system has enough to operate the compressor kicks in and the remainder of the charge is draw in through the low side.

[Johnathan Nagel]

So it’s possible I’m over thinking this and the pressures are so far out of wack the pcm is locking out the ac to prevent damage to the system. And I need to take it somewhere and have the system professionally filled?

[Richard Kirshy]

If you do not have the proper equipment on hand… Vacuum pump, manifold gauge set, system specs ETC.
Also a good working knowledge of automotive AC.
It would be a wise consideration for several reasons.
First if it is broken they can repair it and the repairs are warranty.
So you have some recourse.
Second, if you work on your own and happen to cause damage due to lack of equipment or knowledge.
It will cost you more in the end.

[Author]

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