Can low volts cause AC to not work ?

JOHNPAUL · 09-05-2001, 04:21 PM

Went to the AC shop and vacumed and refilled the system . It was only .5lb low .

I am only reading 13 volts with car running , seems it should be higher ?.

The pressure switch is closed between 2 and 4 .. but always open betwwen 1 and 3 .

I have checked and rechecked all fuses and relays ...I jumped out the switch but the positive reading I got was low .. Do you think it is possible that the climate computer will not send voltage to the comppressor relay in a low voltage situation ?

Is 13 volts ok for the car should I be looking at something else ?

90 964 c4 cab

oc92 · 09-05-2001, 06:30 PM

13 volts is enough output for the alternator/voltage regulator.

Roland Kunz · 09-06-2001, 03:54 AM

Hello

Low voltage troubles is a known problem with the 928 units. However they start at under 11 V so this isn´t direct your issue...

13 Volt at idle is normal. Just switch all circuits and it will trop a bit mostly to 12,3 - 12,5 V.

Grüsse

JOHNPAUL · 09-06-2001, 08:48 PM

Thanks for the input . I'M STILL AT IT . I ordered a new freon pressure switch today , I suspect that the low side of the switch is bad . termenal 2 to 4 are always open ..
But even jumping the switch out will not allow the comressor relay to energize .(1 to 3 , 2 to 4) I know the clutch and relay are good I have tested both , I'm starting to worry that the control unit is bad ....

[This message has been edited by JOHNPAUL (edited 09-06-2001).]

Roland Kunz · 09-07-2001, 07:46 AM

Hello
I´m not sure but the switch has a strange way to work. It controls low/high pressure and switches the condensor fan via a logig relay.

The switch can be changed without loos on the refrigerant as a valve sits inside the block.

Grüsse