Try a Peterbilt dealership.
Right side of the vehicle, under the hood, in the HVAC compartment.
There are a multitude of possibilities here. You need to have a system performance test done to help narrow the cause down.
In the shop manual.
You cannot download the service manual for a 2005 Pontiac Sunfire for free. You will need to call the manufacturer and purchase a new manual.
A 2005 Peterbilt 379 typically requires about 30 ounces (approximately 2.5 pounds) of R134a refrigerant for the air conditioning system. The high-pressure side should generally be between 200-250 psi, while the low-pressure side should be around 25-45 psi, depending on ambient temperatures. Always refer to the vehicle's service manual for the most accurate specifications.
The diagram for the fuse box in a 2005 Caravan can be found in the service manual. The manual might be available for check out at your local library.
You can get one here. www.tradebit.com/filedetail.php/127825290-1995-2005-hyundai-sonata-repair-service-manual
Get one here. [tradebit.com/filedetail.php/9018747-lincoln-ls-2000-2005-service-repair-manual] You can get repair manual information free at FreeAutoMechanic.com [freeautomechanic.com/repairmanuals.html]
or Here 2000-2005 www.tradebit.com/filedetail.php/102815386-hyundai-accent-2000-2005-service-repair-manual 2006-08 here. www.tradebit.com/filedetail.php/9055713-hyundai-accent-2006-2008-service-repair-manual
You can view the 2005 Ford Mustang owners manual online at : www . motorcraft service . com ( no spaces ) Click on Owner Guides
If the vehicle has an automatic transmission, it will have a dipstick. Manual transmissions do not have a dipstick.
The flasher unit is integral to the switch.