Air Brake Compressor Assy compatible for Cummins Engine N14 CELECT NH 855 NT 855 3018534
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HVAC Blower Motor compatible for Kenworth T660 2008-2014/ W900B 1987-2014 740185-2 K1425351
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New Air Brake Compressor 3558006 3558006X compatible for Cummins Engine 6CT 8.3L
1 OfferA/C and Heat: Diagnose Before You Buy
Written by the PickupChain team · Last reviewed October 17, 2026
When the A/C blows warm, the cause can be low refrigerant from a leak, a failed compressor clutch, a clogged condenser or an electrical fault. Recharging without finding the leak only fixes the problem for a short time.
If air comes out weakly from all vents on every speed, check the cabin air filter first. It is a cheap, five-minute job on most trucks. If only some fan speeds work, the blower motor resistor is a common failure.
Refrigerant work on modern trucks often requires certified equipment, especially on vehicles that use R-1234yf refrigerant. Many owners replace bolt-on parts themselves and leave evacuation and charging to a shop.
Frequently Asked Questions
+How often should I replace the cabin air filter?
Every 15,000 to 30,000 miles or once a year is typical, more often on dusty roads. A dirty filter reduces airflow and can cause odors.
+Why does my blower only work on high?
That is the classic symptom of a failed blower motor resistor. The high setting bypasses the resistor, so only that speed keeps working.
+Which refrigerant does my truck use?
Check the label under the hood. Many trucks built since the mid-2010s use R-1234yf, older ones use R-134a. The two are not interchangeable.