Little A/C Help, please. - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Zonaman · 04-09-2010, 07:07 PM

I've got an Old Air 7200 Hurricane unit on my '69. It's been operating flawlessly for the last seven years. Yesterday it was going along fine and the compressor just quit- the fan operates fine. I can't seem to locate the problem. Here's what I've done so far:

* Static pressure is 65 psi at 70 F, both sides- enough to close low-pressure switch, right?
* tested dash switch with test light (light on) and then jumped termial plug (no compressor)
* tested evaporator thermostat terminals with test light- light came on
* Jumped low-pressure switch plug- no compressor. By passed plug entirely and connected wires - no compressor.

* tested reley- a 5 pin. It clicks when dash switch is engaged. With mulit-meter, no power pins 85 & 86 pulled 89 ohms; 30 & 87 0. With power; B+ to 85 & B- to 86, heard a click ; 30 & 87a 0; 30 & 87- 9. I think that's OK.

* All fuses & wires look good.

Did I make any errors or what should I be doing next?

Thanks!

Willys47 · 04-09-2010, 07:56 PM

ohm the cluch on the compressor or just wire it to the batt and that should tell you if the cluch is bad

Zonaman · 04-09-2010, 08:09 PM

Quote:

Originally Posted by Willys47

ohm the cluch on the compressor or just wire it to the batt and that should tell you if the cluch is bad

I presume the one wire leading to the clutch should be connected at the B+ on the battery. How does one get a proper ohm reading off the clutch? It's a Sanden SD5H14.

Thank you.

Chevydude56 · 04-09-2010, 08:57 PM

Connect ohm meter to power wire and to ground/case of compressor.
Have you checked for 12V to the compressor clutch with the system turned on?

Zonaman · 04-09-2010, 09:39 PM

Quote:

Originally Posted by Chevydude56

Connect ohm meter to power wire and to ground/case of compressor.
Have you checked for 12V to the compressor clutch with the system turned on?

I think so- I bypassed the low pressure plug and ran the wire striaght to the compressor.

How many ohms should I see? Does it matter if the system is on?

Thanks guys, this is a great help!

ERASER5 · 04-09-2010, 09:08 PM

Pull the wire off the clutch. Measure ohms from the connector to ground.

1971gmcshortbed · 04-09-2010, 09:02 PM

^ What he said, jump power to the compressor clutch. See if it turns on, if it does work your way back.

hayhauler71 · 04-09-2010, 09:31 PM

Sanden compressors coils have a pretty high failure rate especially if the gap is not correct, if it has power to the compressor try to tap the clutch with a hammer handle while powered up to see if the coil can pull the clutch in.

04-09-2010, 07:07 PM	#1
Zonaman Registered User Join Date: May 2004 Location: Chandler, AZ Posts: 519	Little A/C Help, please. I've got an Old Air 7200 Hurricane unit on my '69. It's been operating flawlessly for the last seven years. Yesterday it was going along fine and the compressor just quit- the fan operates fine. I can't seem to locate the problem. Here's what I've done so far: * Static pressure is 65 psi at 70 F, both sides- enough to close low-pressure switch, right? * tested dash switch with test light (light on) and then jumped termial plug (no compressor) * tested evaporator thermostat terminals with test light- light came on * Jumped low-pressure switch plug- no compressor. By passed plug entirely and connected wires - no compressor. * tested reley- a 5 pin. It clicks when dash switch is engaged. With mulit-meter, no power pins 85 & 86 pulled 89 ohms; 30 & 87 0. With power; B+ to 85 & B- to 86, heard a click ; 30 & 87a 0; 30 & 87- 9. I think that's OK. * All fuses & wires look good. Did I make any errors or what should I be doing next? Thanks! __________________ 69 C-10 LWB, 350, 700r4, 3.73 posi-traction, front disc brakes. Built for the desert- She can take the heat! Vivat Rex Chevus! Last edited by Zonaman; 04-09-2010 at 07:23 PM. Reason: error

04-09-2010, 07:56 PM	#2
Willys47 Registered User Join Date: Dec 2007 Location: Nanaimo B.C. Posts: 604	Re: Little A/C Help, please. ohm the cluch on the compressor or just wire it to the batt and that should tell you if the cluch is bad __________________ I was hooked on these trucks since 1982 when I drove my budys fathers 1968 Custum GMC 396 automatic dana 60 rear with a power lock diff what a ride more fun then we will we can ever tell!!

04-09-2010, 08:57 PM	#4
Chevydude56 Registered User Join Date: Sep 2009 Location: Syracuse NY Posts: 110	Re: Little A/C Help, please. Connect ohm meter to power wire and to ground/case of compressor. Have you checked for 12V to the compressor clutch with the system turned on? __________________ 1967 Suburban 292 3spd 1964 Chevy II wagon 1971 Monte Carlo 402BB 1964 Cadillac series 62 2dr 1964 Bonneville 2dr/ht 1967 GTO 1978 Chevy Van 30 1989 R30 Crew Dually Bonus Cab

04-09-2010, 09:08 PM	#6
ERASER5 Registered User Join Date: Jun 2006 Location: Indiana Posts: 4,859	Re: Little A/C Help, please. Pull the wire off the clutch. Measure ohms from the connector to ground. __________________ '70 GMC C1500 LWB Power disc brakes. WooHoo! Posi 6 Lug Dana 60

04-09-2010, 09:02 PM	#7
1971gmcshortbed Registered User Join Date: Jul 2003 Location: Las Cruces, NM Posts: 284	Re: Little A/C Help, please. ^ What he said, jump power to the compressor clutch. See if it turns on, if it does work your way back. __________________ My build, http://67-72chevytrucks.com/vboard/s...d.php?t=379006

04-09-2010, 09:31 PM	#8
hayhauler71 Registered User Join Date: Aug 2009 Location: St. Paul MN. Posts: 1,996	Re: Little A/C Help, please. Sanden compressors coils have a pretty high failure rate especially if the gap is not correct, if it has power to the compressor try to tap the clutch with a hammer handle while powered up to see if the coil can pull the clutch in.

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