You don't have to know what's wrong with your AC. That's literally the job. Pick the symptom that sounds like yours — here's what it usually means, what gets checked, and where to read more. Every road here ends at the same place: a diagnostic that finds the real answer, at your driveway.
Blowing warm, or not cold at all
Usually low charge from a leak, a compressor that isn't engaging, or a blend door stuck on heat. What gets checked: system pressures, whether the clutch pulls in, and a leak check with UV dye. Read more: AC Compressor, AC Pressure Switches.
Was cold, then went warm again after a recharge
The classic leak story. A recharge without finding the leak just buys a few weeks — the refrigerant escapes again and you're back where you started. The fix is finding the leak, replacing the failed part, then a vacuum and a charge by weight, not by pressure. See it happen: Real Work.
Clicking when the AC kicks on
Often the compressor clutch cycling on low charge, or a clutch on its way out. What gets checked: charge level, clutch engagement, and the clutch coil itself. Read more: AC Compressor.
Noise when the AC is on
Bearing, clutch, or compressor noise — sometimes a fan. The first check is simple: does the noise follow the AC switch, on versus off? Then it gets isolated from there. Read more: AC Compressor.
Cools sometimes, or fades after a while
Low charge, an evaporator freezing up, a pressure switch cutting out, or a fan that isn't pulling air through the condenser. What gets checked: pressures, fan operation, and how the evaporator behaves. Read more: AC Evaporator, AC Pressure Switches.
Smells musty when it starts
Moisture and mildew on the evaporator — it stays damp, and that damp grows things. The fix is cleaning it and making sure the drain is clear so it can dry. Read more: AC Evaporator.
Water inside the car, wet carpet
Usually a clogged evaporator drain backing up into the cabin. Sometimes it's a heater core — that's a different diagnosis, and dash-out heater core work is shop territory, not mobile. What gets checked: drain flow and coolant level. Read more: AC Evaporator.
Rear AC warm while the front still cools
On dual systems, the rear goes warm first on low charge — it's the farthest coil from the compressor. What gets checked: the charge level by weight, because the spec covers both coils. More answers: AC FAQ.
Defroster barely clears the windshield
Defrost starts with the AC: the evaporator dries the air first, then the heater warms it. A weak defroster is often an AC-side problem, not a heater problem. More answers: AC FAQ.
Thinking about a can from the parts store?
Don't. If the system is low, it's low for a reason — usually a leak — and a $70–80 can doesn't fix the reason. It just buys a few weeks and risks overcharging, because a can charges by pressure, not by weight. And if you did the repair yourself and then try to charge it with cans, it definitely won't work: the system is full of air and moisture from sitting open, the drier is saturated, and no can can pull a vacuum. Moisture has to be boiled out under vacuum first, then the system gets a charge by weight. That's the job.
The one answer for all of it
Stop guessing. The $100 diagnostic finds what's actually wrong — pressures, leak check, clutch and fan operation, the full system — and then you get a straight answer and a fair price for the fix. If the system holds a charge, it's the $150 mobile service. Repairs are quoted straight, no dealer numbers. Mobile Car AC comes to you, and most visits take 1–2 hours. See the proof: Real Work. See the prices: Services & Pricing.
Cold Air. Delivered.
📞 661-888-3941 · 🌐 mobilecarac.com
Serving the San Gabriel, San Fernando & Santa Clarita Valleys.