In an attempt to avoid any further confusion I am giving some detailed information on the blower resistors for the Chevrolet Avalanche, Silverado, Tahoe and Suburban, GMC Denali, Sierra, Suburban and Yukon and Cadillac Escalade and midsized Buick Rainier, Chevrolet Trailblazer and SSR (2004+2005), GMC Envoy, Isuzu Ascender and Olsmobile Bravada.
First of all the 15-81772 (formerly the 15-81095) resistor and resistor combo only fit Chevrolet Trailblazers and 2004+2005 SSR, GMC Envoys, Isuzu Acsender and Oldsmobile Bravada with manual a/c controls. The vehicles with auto a/c controls use a blower speed controller that only has three wires in the female connector on the unit. To see diagnostic and repair information on a blower speed controller please click here.
An interior view of a 15-81772.
An exterior view of the 15-81772.
The 15-81772 resistor for Trailblazers and Envoys with 4180 Repair Harness Combo.
The full sized Chevrolet, GMC and Cadillac trucks and SUV’s with manual a/c controls use one of two resistors. The 15-81086 is the most popular by far but a few vehicle details are important. RPO Code CJ3 or C42 ( manual a/c controls) and without RPO D07 ( Factory Floor Mounted Center Console). It is also important to note that a few vehicles do not go by these codes and therefore we strongly recommend a visual inspection of your part. The 15-81086 has a total of four mounting holes in the end tabs. The original design may have used a two part assembly.
The interior view of the 15-81086 resistor.
The exterior view of the 15-81086 resistor.
The full sized Chevrolet, GMC and Cadillac truck Blower resistor and repair harness combo with the 15-81086 resistor.
The 15-81087 resistor is used in full sized trucks and SUV’s with RPO Codes CJ3 (manual a/c controls) and with RPO Code D07 (Factory Floor Mounted Center Console). Again there are a few vehicles that this is not accurate on and a visual inspection is recommended. The 15-81087 is distinguished by only having a total of two mounting holes, one in each of the two end tabs as shown in the following pictures.
The interior view of the 15-81087 resistor.
The exterior view of the 15-81087.
The full sized Chevrolet, GMC and Cadillac truck Blower resistor and repair harness combo with 15-81087 resistor.
When ordering be sure to leave as much information as possible about your vehicle in the customer comment box at check out.
In the picture from my site, you can only see the outside connector. I am including a link to the part. Please test your system first to confirm it will fix your problem. Your 1999 Suburban 2500 only used the old body style design. The Silverado and Sierra models could have either design depending on which body style the truck is, new or old.
http://store.the-electric-connection.com/15-8788-blower-resistor-p549.aspx
It is located behind the glove box on top of the heater-a/c case.
http://www.sparkys-answers.com/2010/11/1997-gmc-c1500-pickup-no-blower.html
http://www.sparkys-answers.com/2010/11/1997-gmc-c1500-pickup-no-blower-part-2.html
http://www.sparkys-answers.com/2010/11/1997-gmc-c1500-pickup-no-blower-part-3.html
I have a 1999 Chevy Suburban 2500 (7.4L) which has only had fan speeds 4 and 5, but now none.
The blower runs fine if wired direct.
Both fan fuses (20A and 50A) are good under hood,
What resistor do I need?
Where is the Blower Resistor located n the 1999 Suburban 2500 ?
You have tested the power signal inputs to the blower speed controller. Now you just have to check the output to the blower motor. If the signals to the blower motor are not present, the blower speed controller is faulty. If I remember correctly I diagnosed a faulty blower speed controller, replaced it and followed it up with some confirmation tests.
2004 silverado with automatic fan control. Tested speed controller as shown in your video with the same voltage results…1.5 v with fan on high and 4.5 to 5 v on low. Was your YouTube video testing a bad speed controller or a good one?