Frequently Asked Questions About Kenworth T680 Heat & AC Parts
Will these HVAC parts fit my specific year model T680, and are there differences between the standard and high-roof sleeper configurations?
Most heat and AC components for the T680 are compatible across model years 2013-present, but there are important exceptions. Blower motors, evaporator cores, and heater cores typically fit all years. However, control panels and some wiring harnesses changed in 2017 with the updated dash design. High-roof sleeper models require different ductwork and may need extended refrigerant lines. Always verify your OEM and sleeper configuration when ordering to ensure proper fitment.
What are the most common signs that my T680's heater core or evaporator needs replacement, and how difficult is the installation?
Key indicators include sweet coolant smell in the cab (heater core), foggy windshield that won't clear, wet passenger floor mats, or weak airflow with proper blower operation. Evaporator issues typically show as poor cooling, musty odors, or water dripping inside the cab rather than underneath. Installation difficulty varies significantly - blower motor replacement takes 30-45 minutes, while heater core replacement requires dash removal and can take 6-8 hours. We recommend professional installation for heater cores and evaporators unless you have substantial HVAC experience.
Are aftermarket AC compressors and condensers as reliable as OEM parts for my T680?
Quality aftermarket options from established manufacturers like Red Dot, Bergstrom, and Four Seasons perform comparably to OEM parts when properly installed. These units typically carry 1-2 year warranties and cost 30-50% less than Kenworth OEM components. The key is ensuring correct refrigerant capacity and fitting specifications. Avoid unbranded imported compressors, as they often fail prematurely due to poor clutch quality or inadequate oil retention.
What refrigerant type does my T680 use, and how much does the system hold?
All T680 models from 2013 onward use R-134a refrigerant. Standard day cab models hold approximately 2.5 lbs, while sleeper models require 3.0-3.5 lbs depending on the sleeper size and auxiliary AC configuration. Never mix refrigerant types, and always evacuate and recharge the system when replacing major components. Some 2021+ models may have transitioned to R-1234yf - check the label under your hood for verification.
Which blower motor resistor or control module do I need if my fan only works on high speed?
The T680 uses an electronic blower motor control module rather than a traditional resistor. Part numbers vary by production date: pre-2017 models typically use module F21-1008-101, while 2017+ models with the updated electrical system require F21-1025-100. This module is located behind the glove box and controls all fan speeds through pulse-width modulation. If your blower only works on high, the module has likely failed - the blower motor itself rarely causes single-speed operation.
