--- title: Heater Blowing Cold Air: Common Causes and What to Check url: https://xpressoilandlube.com/problems/heater-blowing-cold/ business: Xpress Oil & Lube (Xpress Oil & Lube Center) shops: Reno Northwest: 6100 Mae Anne Ave, Reno, NV 89523, (775) 787-1000, Mon-Fri 8 am-5 pm, Sat 8 am-4 pm, Sun closed; Reno South: 4993 Longley Ln, Reno, NV 89502, (775) 828-6996, Mon-Fri 8 am-5 pm, Sat 8 am-3 pm, Sun closed; Carson City: 1861 E College Pkwy, Carson City, NV 89706, (775) 883-5823, Mon-Fri 8 am-5 pm, Sat 8 am-4 pm, Sun closed; Gardnerville: 1293 US Hwy 395 N, Gardnerville, NV 89410, (775) 301-5912, Mon-Fri 9 am-5 pm, Sat 9 am-3 pm, Sun closed type: Drive-in oil change and vehicle maintenance, no appointment needed, since 1983 --- Today's coupons - $10 off full-service oil change - $5 off smog check - $25 off transmission fluid service [See all coupons](https://xpressoilandlube.com/coupons/) - [Home](https://xpressoilandlube.com/) - [Problems](https://xpressoilandlube.com/problems/) - Heater blowing cold air # The heater is blowing cold air A heater that stays cold usually means the engine is low on coolant, the thermostat is stuck open, or hot coolant is not reaching the heater core. Check the coolant level with the engine cool today, because low coolant can also mean the engine overheats. ★★★★★ 4.7 stars from 952 Google reviews Drive in today General guidance for this symptom. A warning light that is flashing or an overheating engine: stop driving and call. ## Likely causes - Low coolant The heater core usually sits high in the system, so it is the first place to run dry when the level drops. Air in the system after a top-off can do the same thing. Low coolant also means less protection against overheating. [Coolant flush and cooling system service](https://xpressoilandlube.com/services/coolant-flush/) - A thermostat stuck open If the thermostat never closes, the engine runs cool, the temperature gauge sits lower than usual and the heater only gets lukewarm. A repair shop replaces thermostats. [Multi-point maintenance check](https://xpressoilandlube.com/services/maintenance-check/) - A clogged heater core Old coolant breaks down and leaves scale. The narrow heater core passages are often where it collects first, and flow drops off over time. [Coolant flush and cooling system service](https://xpressoilandlube.com/services/coolant-flush/) - A blend door or control fault If the engine is warm, the coolant is full and both heater hoses are hot, the problem is inside the dash: a door actuator or control that will not move to the heat side. That is repair shop work. [Multi-point maintenance check](https://xpressoilandlube.com/services/maintenance-check/) Your heater is a small radiator behind the dash that borrows heat from engine coolant. If the coolant is low, never gets hot, or cannot flow through that small radiator, the fan blows outside-temperature air. On a Gardnerville morning in January that is miserable, and it also clears the windshield poorly, which makes it a safety issue on US-395 before sunrise. ## Three things to notice before you come in - Where the temperature gauge sits once warmed up, compared with what you are used to - Whether the air gets warm at highway speed but cold at idle (often low coolant or air in the system) - Whether the fan blows hard or barely moves air (weak airflow points to the blower or a clogged cabin filter) A weak fan is a different problem from cold air. A [cabin air filter](https://xpressoilandlube.com/services/cabin-air-filter/) that is packed with dust and smoke residue can choke airflow, and that one we replace in the bay. ## What we check and what we hand off We check the coolant level and strength, look for leaks at hoses and the radiator, and check the cabin filter. If the coolant is low or worn out, a [coolant flush](https://xpressoilandlube.com/services/coolant-flush/) replaces it with the type your manual lists and purges air from the system. A flush can sometimes restore flow through a partly scaled heater core, though it cannot clear a fully blocked one. Thermostats, heater core replacement and dash controls are repairs we do not perform. We tell you what we found and point you to a repair shop. You decide. ## Why it shows up in the first cold week Reno averages about 122 nights a year at or below freezing, Carson City about 146 and Minden about 188 (NOAA 1991-2020 normals). A heater that was only a little weak in October becomes obvious in November. The Car Care Council suggests checking the cooling system before winter for this reason, and our [before-winter checklist](https://xpressoilandlube.com/checklists/before-winter/) includes it. ### Sources - [ncei.noaa.gov/products/land-based-station/us-climate-normals](https://www.ncei.noaa.gov/products/land-based-station/us-climate-normals) (NOAA 1991-2020 climate normals: Reno-Tahoe airport 65 days a year at 90 F or more and 122 nights at or below 32 F, Carson City 146 freezing nights, Minden 188; read 10/15/26) - [carcare.org/car-care-guide/](https://www.carcare.org/car-care-guide/) (Car Care Council Car Care Guide: inspect fluids, belts, hoses, filters, battery, lights and wipers at regular intervals; read 10/15/26) ### Your service center: Reno Northwest - Call [(775) 787-1000](tel:+17757871000) Mon-Fri 8 am-5 pm, Sat 8 am-4 pm, Sun closed - Address 6100 Mae Anne Ave, Reno, NV 89523 [Directions](https://www.google.com/maps/dir/?api=1&destination=6100+Mae+Anne+Ave%2C+Reno%2C+NV+89523&destination_place_id=ChIJ3dFA7yBEmYARYg1CtQTi_Bk) ### Related - [Coolant keeps dropping with no visible leak](https://xpressoilandlube.com/problems/coolant-low-no-leak/) - [Engine overheating](https://xpressoilandlube.com/problems/engine-overheating/) - [Getting your car ready for a Reno winter](https://xpressoilandlube.com/guides/winter-car-prep-reno/) - [Winter](https://xpressoilandlube.com/seasonal/winter/) - [Coolant flush and cooling system service](https://xpressoilandlube.com/services/coolant-flush/) Drive in. No appointment. Drive out. Locally owned in Northern Nevada since 1983. No appointment, no pressure: we tell you what the inspection found and you decide. [About us](https://xpressoilandlube.com/about/) ## What we do about it [### Coolant flush and cooling system service Learn more](https://xpressoilandlube.com/services/coolant-flush/)[### Multi-point maintenance check Learn more](https://xpressoilandlube.com/services/maintenance-check/)[### Cabin air filter Learn more](https://xpressoilandlube.com/services/cabin-air-filter/) ## Questions people ask Still have a question? Call your service center or drive in; there is no appointment to make. ### My heater works on the highway but blows cold at stop lights. Why? That pattern often means the coolant is low or there is air in the system, so flow drops at idle. Check the level when the engine is cool and come in. ### Is it safe to drive with no heat? The car may run fine, but low coolant can lead to overheating, and a cold cabin makes the windshield harder to clear. Get it checked today. ### Will a coolant flush fix my heater? It fixes heat loss caused by low or worn-out coolant and air pockets. It does not fix a stuck thermostat or a broken blend door. ### Why is my temperature gauge lower than normal? A gauge that sits low once warmed up often points to a thermostat stuck open. A repair shop can confirm and replace it.