I need some a/c advice on my 96 Rover SE. The a/c will not come on. When I hotwire a 12v to the compressor, it comes right on and blows very cold. It is not getting voltage from the wiring harness coming to the plug on the compressor. It has a new trinary valve and r134 charge, any ideas/advice before I run a 12v switch strait to the compressor?

 

I gave up on charging mine using normal means, when I read the manual it's like a lesson in physics.
Stick a thermometer in the dash outlet & make sure you're above 45deg discharge or you may damage the compressor

I'd check for the low pressure switch to be made (low pressure side of a/c)
ditto for high pressure cutout (high pressure side)
Lastly, check your fuse, relays. I believe if the condensor fans are disabled (relay, fuses), then the compressor also will not come on.

Jumping is not a solution, if you do, make sure of the temps & condesor fans - NO frost allowed on suction side, sweat ok tho'

 

thanks for the advice! I just bought a new low pressure switch from atlantic british, but I hate to put it on and discharge the system again. Starting to feel like im just throwing parts at the a/c system to get it going. Im about $450 deep on the a/c system now with no resolve. I dont have a Rover stealership in my state and the only local person who works on them took me to the cleaners on trying to diagnose this issue. Ive checked all fuses/relays and they seem fine.

 

I don't have the connector in front of me , but can you unplug, jump the wires w/a paper clip? That would fool it into thinking the switch was closed?

Same if there's a high pressure cutout.

(I use an inline fuse holder to jump alot of things, (new style fuses, easy to switch amps) to test circuits.)) $2 @ auto parts &buy a fuse ***'t pkg.

I agreeabout blowing the charge - The irritating part is that mine would work intermittently, I checked for a weekend & never found the problem.
& I'm a diagnostic tech & mechanic - go figure.

I read some time ago about the connections on the board under the main relay/ fuse panel (behind the batt) would burn.
I believe you might see discoloration under the relays if so. Otherwise you have to pull the box loose & look underneath it.
just a thought.

 

I jumped the high/low with a paperclip, nothing...

I checked the relays and there apprears to be no discoloration, nothing...

I made sure all electrical connections were tight, nothing...

Im scratching my head on this. No voltage to compressor, when I hotwire it, it cools like a champ!!

what would it harm to wire a 12v hot on a toggle switch to the compressor?

 

I dunno, Logically, the signal to pull in the compressor would be from a relay through a fuse ( probably only from the engine compartment fusebox).
I'd disconnect the battery (I've done it on mine several times) then,I'd put an ohmeter from the output (loadside) terminal of the A/C relay to the
power in @ the compressor clutch.
If it showed open, then I'd start tracing wires & points from there. Your connections may look ok at a glance, but you're beyond that.
Electrical can drive you nuts, but most of the time it turns out to be something simple.
I'd trace the harness inspecting it for cuts, abrasions, pinches etc. Pull apart all connectors, stick the ohmeter in each end as you go.

The main harm to the compressor could be slugging, (When the charge is cold & low) caused by too much liquid coming back. Liquid 134a doesn't compress well & beats the compressor to death. Usually your suction (larger) line @ the compressor will start icing first tho'

I looked in my rave cd, & the HVAC wiring diagram has a crapload of connections which include the BECM(computor), solar sensor, interior temp sensor,
Outside temp sensor, on&on&on.
By the way, that little slotted circle below your radio?
Look into it w/a flashlight & see if there's dust ***** stopping the little tiny fan - I hope you saved your paper clip - be careful, the fan's fragile.

 

Stealership? I might be able to walk you through this problem, But I take offense to your comment! Good luck!! Certified Land Rover Tech with over 15 years exp!!!

 

FUNNY, too bad you take offense so easily. Life is too short, its just a joke.

 

bump for any a/c help/advice....

 

trinary switch is never the fix, you already found this out though. generaly is it poor charge, however ive seen several hvac heads cause this problem. and, hopefully not in your case, a few becm's too.


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