Evaporator, Blower & Heater Core

With the cabin filter, which is the cheapest part in this category and the cause of most airflow complaints. A filter that has been in place for a couple of years is often visibly grey and packed with leaf debris, and it restricts flow at every fan speed while the blower works perfectly. Change it, run the fan through its range, and reassess. If flow is still weak with a new filter, look at the blower, the flaps and the ducts.

The blower speed control module, in nearly every case. Lower speeds are produced by controlling the current to the motor, and the highest setting on many systems bypasses that control entirely and feeds the motor directly, which is why a failed module leaves exactly one working speed. It is a well known and easily identified fault. The module usually sits in the airflow to keep it cool, so it is accessible on many vehicles without dismantling the dashboard.

Because the evaporator is cold and wet whenever the system runs, and that is an ideal environment for microbial growth on its fins, particularly on a vehicle used for short journeys where the core never dries out. The smell is strongest in the first seconds after the fan starts. A specialist cleaning treatment applied to the evaporator, along with a new cabin filter, usually resolves it. Switching the compressor off a few minutes before the end of a journey lets the core dry.

That is the evaporator condensate that should be leaving through a drain tube under the car. The tube blocks with leaf debris and the fine dust that gets past a tired filter, the tray overflows and water finds the carpet, usually on the passenger side. Clearing the drain with low pressure air or a soft trimmer line cures it. Do this before ordering anything, and dry the carpet properly, since a soaked underlay causes damp and corrosion long after the leak is fixed.

On most vehicles it is one of the larger interior jobs there is, because the evaporator sits inside a case behind the dashboard and reaching it means removing the dashboard and often the cross car beam. It also means opening the refrigerant circuit, which requires recovery and recharging with the correct equipment. That combination is why an evaporator leak is expensive relative to the part. Have the leak confirmed properly before committing, since the labour dwarfs the component.

Cabin filters, duct sections and clips sit right at the bottom of the range. Blower speed control modules and blower assemblies are moderate. Evaporators, evaporator cases and interior condensers cost the most in this category, and their fitting cost is higher again. The live minimum and maximum are shown in the band at the top of this page. Since a filter explains most complaints here, starting cheap genuinely pays.

At the manufacturer's interval, and sooner in dusty conditions or if you park under trees. Many owners find annual replacement sensible. Beyond airflow, the filter protects the evaporator from the debris that feeds microbial growth and blocks the condensate drain, so a neglected filter creates the two most common complaints in this category. It is among the least expensive parts on the site and one of the few in this group an owner can change in minutes.

Frequently yes, since it is usually accessible from the passenger footwell behind a cover, held by three screws and a connector. The speed control module is often alongside it. What sends this job to a workshop is when the blower sits inside a case that only opens with the dashboard out, which some vehicles do. Check access before ordering, and while you are there inspect the housing for debris, since leaves that got past the filter end up in the blower.

Because the distribution flaps or the ducts are at fault rather than the blower. A flap actuator that has stripped its gears leaves the flap in one position, so air continues to arrive at whichever outlet that setting selects, and a duct that has cracked or come adrift behind the dashboard leaks air into the cavity instead of delivering it. The ducts are listed here individually, which makes the second case far cheaper to fix than it sounds.

It is an additional heat exchanger inside the climate case that releases heat from the refrigerant circuit into the cabin air, allowing the vehicle to heat by moving heat rather than generating it. On a conventional system that job is done by a heater core carrying hot coolant. Its presence makes the case assembly more complex and means a climate fault on such a vehicle can involve the refrigerant circuit even when the complaint is about heating rather than cooling.

Check the number, since climate hardware varies with specification. Vehicles with automatic climate control, rear vents, heat pumps or air quality sensing carry different cases, ducts and flap arrangements to base versions, and visible parts also differ by interior colour. A duct that is nearly right leaks air where it matters. Match the OE number, and use the quote form where the reference brings back nothing so the catalogue is checked against your vehicle.

Yes. Cabin filters and blower motors are usually priced. Evaporators and heater cores are the references that tend to need an enquiry, partly because they are ordered rarely and partly because each is built for one climate specification. Send the number and a figure follows. Before you order either, be as sure as you can that the core is genuinely at fault, because both sit behind the instrument panel and the labour dwarfs the part. A blocked drain, a jammed blend flap or a tired blower can all produce symptoms that look like a failed core from the driver's seat.