# Car AC Repair in Upland > Car AC blowing warm, weak or smelly? Route 66 Auto Repair in Upland measures vent temps and pressures, finds the leak and fixes the real cause. Source: https://route66autorepairshop.com/cooling-heating-ac-services/car-ac-repair Updated: 2026-09-17 Business: Route 66 Auto Repair, 1775 W Foothill Blvd, Upland, CA 91786, (909) 608-7699 Hours: Monday to Friday 8 AM–5 PM, Saturday 8 AM–2 PM, Sunday closed **TLDR:** Warm air has many causes. We sort them by **symptom**, confirm with **gauge readings**, and fix the failed part instead of just refilling a leaking system. If your car AC is blowing warm, barely moving air, or smells musty, Route 66 Auto Repair in Upland can find out why and fix it. We read vent temperature and system pressures, check whether the compressor engages, and look for leaks before adding any refrigerant. ASE-certified technicians do the testing, and you see a written estimate before the repair begins. ## What are the signs your car AC needs repair? - Air starts cold but fades to warm after a few minutes - Cold on the highway, warm while idling at a light - Air is cold on one side of the car and warm on the other - Airflow is weak even on the highest fan speed - A clicking, grinding or squealing sound when the AC is switched on - Water on the passenger floor or a musty smell from the vents ## What does each symptom usually point to? Warm on one side only is often a blend door actuator, not a refrigerant problem, and we check it before connecting gauges. Weak airflow usually lives on the air side: a clogged cabin filter, a failing blower or debris in the case. Warm at idle but cold at speed leans toward condenser airflow and the fan. Noise with the AC on points to the compressor, its clutch or a pulley. Air that simply never gets cold is the widest category. It can be a leak, a clutch that never engages, a failed pressure sensor, or a blown fuse. That is where our [AC system diagnostic](https://route66autorepairshop.com/cooling-heating-ac-services/ac-system-diagnostic) earns its keep, and where a [leak detection](https://route66autorepairshop.com/cooling-heating-ac-services/ac-system-leak-detection) test comes before any refill. There is a rough yardstick for how cold is cold enough. On a system in good shape, the air at the center vent commonly measures about 20 to 30 degrees below the air going into the system once the blower has run for a few minutes at moderate outdoor temperatures. On a 105 degree afternoon, expect the gap to narrow. We record the vent temperature and the pressures on your repair order and compare them with the figures your vehicle maker publishes for the test conditions of the day. ## Our car AC repair process 1. **Confirm the complaint:** We run the AC with you or from your notes and record the center vent temperature. 2. **Sort air side from refrigerant side:** Blower, filter and door checks come before gauges. 3. **Gauge and scan:** Pressures are compared to ambient temperature, and module data is read for sensor faults. 4. **Locate and quote:** Leaks or failed parts are pinpointed and written up with photos where useful. 5. **Repair, charge, verify:** After repair we evacuate, charge by weight and record the new vent temperature on a road test. ## What's included in car AC repair - Vent temperature reading before and after - Blower, cabin filter and blend door check - High and low side pressure readings - Leak check before refrigerant is added - Charge by weight to the refrigerant your vehicle specifies - Road test with the AC running ## How pricing and timing work A blend door actuator, a relay and a compressor sit at very different price points, so we give ranges on the phone and a firm written estimate after testing. Refrigerant is listed as its own line. If we open a sealed system and find more wear, we stop and call you. Relay, filter and recharge jobs are often done the same day when the board allows. See the [cooling, heating and AC hub](https://route66autorepairshop.com/cooling-heating-ac-services) for how we handle bigger jobs. ## Frequently asked questions ### Why does my AC work sometimes and not other times? Intermittent cooling often comes from a clutch with a worn air gap, a relay that sticks, a pressure sensor near its limit, or an evaporator that ices up on long drives. Tell us when it happens so we can recreate it during testing. ### Can I drive with a broken AC? Usually yes, if the problem is only warm air. If the compressor is grinding or the belt squeals, get it checked soon, because a seized compressor or pulley can throw the drive belt that also runs other engine parts. ### Do you fix AC on trucks and SUVs with rear air? Yes. Rear AC adds long lines under the body and a second evaporator, which are common leak spots. We test both circuits and include them in the written estimate. --- Call (909) 608-7699 or visit https://route66autorepairshop.com/contact for a written estimate.