AC only blows on HI.........wtf? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

88Jimmy4x4 · 06-18-2005, 02:06 PM

My AC in my burb will only blow on HI fan speed, anything other setting is like its turned off. It was working fine and just started this.

Is it the controls? relay? I dunno wtf

Anyone know whats wrong?

Earl Filter · 06-18-2005, 02:19 PM

Blower motor resistors - common, easy to replace and cheap. There's about a 98% chance that's what it is. They're what gives you any fan speeds other than high.

EDIT: A quick check at rockauto.com says you'll be out between $9 and $11 for it. I don't know these trucks all that well, but the resistor pack is either going to be on or near the passenger side firewall, or under the passenger side dash. It's going to be near the blower somewhere! I just saw you're in Sealy...I'm only 1/2 hour away! Any parts store should carry it, by the way.

BALDMIKE · 06-18-2005, 03:11 PM

Well you're lucky, mine only blows on low and medium, high is out.

I was told it was a fan relay ?

Anyone have a link or part # ?

Slonaker · 06-18-2005, 10:16 PM

Quote:

Originally Posted by BALDMIKE

Well you're lucky, mine only blows on low and medium, high is out.

I was told it was a fan relay ?

Anyone have a link or part # ?

Check the wiring. The high position uses a separate wire. It has a connector in it, and they sometimes burn up. I had it happen on my old Cutlass, and have seen several people report it happening on their truck.

The connector on my Cutlass ran across the top of the engine, and the connector was near the carb. I can't remember if it is there on the truck or somewhere else.

Slonaker

88Jimmy4x4 · 06-18-2005, 07:43 PM

Thanks Earl, located the part on the condensor shroud under the hood.

I hope o-reilly carries it.

gchemist · 06-18-2005, 08:38 PM

Replace the fan relay. I had the same problem. I paid like $5 for the relay.

88Jimmy4x4 · 06-18-2005, 09:38 PM

Quote:

Originally Posted by gchemist

Replace the fan relay. I had the same problem. I paid like $5 for the relay.

Okay well both parts are on the condensor housing shroud, now which one do I try first?

Earl Filter · 06-19-2005, 12:02 AM

Quote:

Originally Posted by 88Jimmy4x4

Okay well both parts are on the condensor housing shroud, now which one do I try first?

Mine. Trust me.

*1FaastC10* · 06-19-2005, 12:23 AM

there is no such thing as a condenser shroud, the condensor is mounted in front of the radiator.

ElGracho · 06-19-2005, 01:13 AM

Quote:

Originally Posted by 1FaastC10

there is no such thing as a condenser shroud, the condensor is mounted in front of the radiator.

Yep, it's the evaporator case.

With it working on high, the relay works. Not working on the other speeds is the resistor, interconnecting wiring, or a switch failure on your controller just like others have said. I'd go with the resistor first.

88Jimmy4x4 · 06-19-2005, 10:01 AM

Okay well I removed the resistor, but looking at it everything seems fine. If its bad would one of the springs or something be broken or loose?

88Jimmy4x4 · 06-19-2005, 10:05 AM

oh and theres actually 2 different resistors locations, one goes to the blower motor and looks like this:http://198.208.187.182/servlet/com.e...partnbr=336403

the other one is located on the opposite side and just has a connector and the wires go into the firewall and looks like this:http://www.smpcorp.com/web_app/catalog/images/RU64.jpg

I assume its the first one since it joins the wire harness that goes to the blower motor, is this correct?

NeCrOmAnCeR · 06-19-2005, 10:06 AM

Yes, they would look burnt. Time to check the switch or wiring to the fuse box (assuming you already checked the fuse).

Usually when the resistor block blows, only one of the resistors goes bad, therefore you will loose low and one of the intermediate speeds. Not saying that both cannot be blown at the same time, but assuming all speeds worked since you have had the truck you are more likely to notice two of the speeds stopped working before the resistor block goes totally bad.

Looks like you were typing while I was. Wouldn't hurt to check both, but the one which connects to the blower motor is the one.

88Jimmy4x4 · 06-19-2005, 04:52 PM

well o-reillys doesnt carry the blower motor resistor part and rockauto.com wants $8.93 for the part and $8.75 for shipping so its still not fixed, guess I will check parts stores in Houston while Im at work tomorrow.

Side note: I can unplug the connector from the resistor and the system works the same only on HI FAN speed.

If it were a fuse, I would assume it wouldnt work at all right (not even on HI)?

jimfulco · 06-20-2005, 01:01 AM

Sometimes you have to get the switch lever in EXACTLY the right position before it will pass juice. Also, wiggle all your electrical connectors & see if it's just some corrosion on the contacts that's causing the problem.

gchemist · 06-20-2005, 01:51 AM

Take a voltmeter and check the relay!!! IT'S THE RELAY!!!

88Jimmy4x4 · 06-21-2005, 10:06 PM

Quote:

Originally Posted by gchemist

Take a voltmeter and check the relay!!! IT'S THE RELAY!!!

I removed the resistor, looked good, measured ohms good, and was getting voltage so I knew that wasnt it.

Next....the relay....yup that was it, problem fixed...gchemist was right

Thanks

88Jimmy4x4 · 06-20-2005, 10:58 AM

Its kinda weird, when you first turn it on it blows cold on HI, if you lower the lever one notch it will blow, then cutoff...then blow...then cutoff for good till you move the lever to hi then it blows fine...kinda weird like something heats up then doesnt work.

88Jimmy4x4 · 06-20-2005, 04:52 PM

does anyone have the electrical schem for the ac system online?

06-18-2005, 02:06 PM	#1
88Jimmy4x4 Registered User Join Date: Oct 2003 Location: houston, texas Posts: 1,974	AC only blows on HI.........wtf? My AC in my burb will only blow on HI fan speed, anything other setting is like its turned off. It was working fine and just started this. Is it the controls? relay? I dunno wtf Anyone know whats wrong? __________________ 2008 Silverado Z71 RCSB 1991 GMC Jimmy 4x4 1976 GMC Sierra C15 SWB

06-18-2005, 02:19 PM	#2
Earl Filter Registered User Join Date: May 2005 Posts: 212	Blower motor resistors - common, easy to replace and cheap. There's about a 98% chance that's what it is. They're what gives you any fan speeds other than high. EDIT: A quick check at rockauto.com says you'll be out between $9 and $11 for it. I don't know these trucks all that well, but the resistor pack is either going to be on or near the passenger side firewall, or under the passenger side dash. It's going to be near the blower somewhere! I just saw you're in Sealy...I'm only 1/2 hour away! Any parts store should carry it, by the way. __________________ Real Name - Brandon Current Vehicles: 1977 C20 Silverado 454/TH400 3.73s 1989 Jaguar XJ6 in the middle of an LT1/4L60E swap Last edited by Earl Filter; 06-18-2005 at 02:23 PM.

06-18-2005, 03:11 PM	#3
BALDMIKE Enormous Member Join Date: May 2005 Location: CLOUD "9" Posts: 108	Well you're lucky, mine only blows on low and medium, high is out. I was told it was a fan relay ? Anyone have a link or part # ? __________________ "79" Chevy Stepside 350/350 Check my Blog @ www.BaldMikesWorld.blogspot.com

06-18-2005, 07:43 PM	#5
88Jimmy4x4 Registered User Join Date: Oct 2003 Location: houston, texas Posts: 1,974	Thanks Earl, located the part on the condensor shroud under the hood. I hope o-reilly carries it. __________________ 2008 Silverado Z71 RCSB 1991 GMC Jimmy 4x4 1976 GMC Sierra C15 SWB Last edited by 88Jimmy4x4; 06-18-2005 at 09:58 PM.

06-19-2005, 10:01 AM	#11
88Jimmy4x4 Registered User Join Date: Oct 2003 Location: houston, texas Posts: 1,974	Okay well I removed the resistor, but looking at it everything seems fine. If its bad would one of the springs or something be broken or loose? __________________ 2008 Silverado Z71 RCSB 1991 GMC Jimmy 4x4 1976 GMC Sierra C15 SWB

06-18-2005, 08:38 PM	#6
gchemist BAD BOW-Silverado XST Join Date: May 2000 Location: Senior Member from Austin, TX Posts: 6,431	Replace the fan relay. I had the same problem. I paid like $5 for the relay.

06-19-2005, 12:23 AM	#9
1FaastC10 Account Suspended Join Date: Oct 2002 Location: Elkhart, IN Posts: 6,399	there is no such thing as a condenser shroud, the condensor is mounted in front of the radiator.

06-19-2005, 10:05 AM	#12
88Jimmy4x4 Registered User Join Date: Oct 2003 Location: houston, texas Posts: 1,974	oh and theres actually 2 different resistors locations, one goes to the blower motor and looks like this:http://198.208.187.182/servlet/com.e...partnbr=336403 the other one is located on the opposite side and just has a connector and the wires go into the firewall and looks like this:http://www.smpcorp.com/web_app/catalog/images/RU64.jpg I assume its the first one since it joins the wire harness that goes to the blower motor, is this correct? __________________ 2008 Silverado Z71 RCSB 1991 GMC Jimmy 4x4 1976 GMC Sierra C15 SWB

06-19-2005, 10:06 AM	#13
NeCrOmAnCeR Registered User Join Date: Feb 2004 Location: Hodgenville, Ky Posts: 735	Yes, they would look burnt. Time to check the switch or wiring to the fuse box (assuming you already checked the fuse). Usually when the resistor block blows, only one of the resistors goes bad, therefore you will loose low and one of the intermediate speeds. Not saying that both cannot be blown at the same time, but assuming all speeds worked since you have had the truck you are more likely to notice two of the speeds stopped working before the resistor block goes totally bad. Looks like you were typing while I was. Wouldn't hurt to check both, but the one which connects to the blower motor is the one. Last edited by NeCrOmAnCeR; 06-19-2005 at 10:08 AM.

06-19-2005, 04:52 PM	#14
88Jimmy4x4 Registered User Join Date: Oct 2003 Location: houston, texas Posts: 1,974	well o-reillys doesnt carry the blower motor resistor part and rockauto.com wants $8.93 for the part and $8.75 for shipping so its still not fixed, guess I will check parts stores in Houston while Im at work tomorrow. Side note: I can unplug the connector from the resistor and the system works the same only on HI FAN speed. If it were a fuse, I would assume it wouldnt work at all right (not even on HI)? __________________ 2008 Silverado Z71 RCSB 1991 GMC Jimmy 4x4 1976 GMC Sierra C15 SWB

06-20-2005, 01:01 AM	#15
jimfulco Registered User Join Date: May 2003 Location: Shreveport LA Posts: 3,170	Sometimes you have to get the switch lever in EXACTLY the right position before it will pass juice. Also, wiggle all your electrical connectors & see if it's just some corrosion on the contacts that's causing the problem.

06-20-2005, 01:51 AM	#16
gchemist BAD BOW-Silverado XST Join Date: May 2000 Location: Senior Member from Austin, TX Posts: 6,431	Take a voltmeter and check the relay!!! IT'S THE RELAY!!!

06-20-2005, 10:58 AM	#18
88Jimmy4x4 Registered User Join Date: Oct 2003 Location: houston, texas Posts: 1,974	Its kinda weird, when you first turn it on it blows cold on HI, if you lower the lever one notch it will blow, then cutoff...then blow...then cutoff for good till you move the lever to hi then it blows fine...kinda weird like something heats up then doesnt work. __________________ 2008 Silverado Z71 RCSB 1991 GMC Jimmy 4x4 1976 GMC Sierra C15 SWB

06-20-2005, 04:52 PM	#19
88Jimmy4x4 Registered User Join Date: Oct 2003 Location: houston, texas Posts: 1,974	does anyone have the electrical schem for the ac system online? __________________ 2008 Silverado Z71 RCSB 1991 GMC Jimmy 4x4 1976 GMC Sierra C15 SWB



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