Where is the heater core on a Lexus IS250?

In short, the heater core sits inside the dashboard HVAC unit on the passenger side, behind the glove box. Access typically requires removing the glove box and nearby dash panels to reach the heater core housing.

More details: The heater core is a small, radiator-like component inside the climate control/heater assembly. In the IS250, this unit sits behind the passenger-side portion of the dash, with coolant hoses running through the firewall on that side. Replacement or service usually means partial disassembly of the lower dash and glove box to reach the core.

Location and structure

The heater core itself is located within the HVAC housing on the passenger side of the cabin, not under the hood. It is fed by hot coolant from the engine via hoses that connect to the core through the firewall. The core is secured inside the heater case behind the glove box area and is accessed by removing panels and the glove box as needed for service.

How to access the heater core (general steps)

To access the heater core, technicians typically work from the passenger side footwell and center console area. Steps can vary by model year, trim, and whether you’re just inspecting or replacing the core.

• Disconnect the negative battery cable and drain a portion of the cooling system if you plan to disconnect coolant hoses.


• Lower or remove the glove box to expose the HVAC housing on the passenger side.


• Remove any dash trim or panels that cover the heater core access area.


• Unseal or remove the HVAC housing access panel to reach the heater core and its hoses.


• Carefully disconnect the heater hoses from the core, noting routing for reassembly.


• Remove the heater core from its housing, then replace or reseal and reassemble in reverse order.

Concluding note: Access to the heater core is a labor-intensive task that often requires specialized tools and careful handling of the dashboard components. If you’re unsure, consult a professional mechanic. After reassembly, refill and bleed the cooling system to prevent air pockets and overheating.

Summary

The Lexus IS250’s heater core is housed inside the dash in the passenger-side HVAC unit, behind the glove box. Access typically involves removing the glove box and related dash panels to reach the heater core and its hoses. Replacement or inspection should be approached with careful disassembly and proper coolant bleeding.

Why is the heater not working on my Lexus IS250?

A Lexus IS250's heater may not be working due to a low coolant level, which prevents coolant from reaching the heater core. Other common causes include a faulty thermostat, an air pocket in the cooling system, a problem with the blend door motor or actuator, or a clogged or failing heater core. Less common issues could involve the cabin air filter, a blown fuse, or a faulty blower motor.
 
Troubleshooting steps 
This video demonstrates how to check and potentially fix issues with your cabin air filter: 1mGarageKingYouTube · Dec 4, 2021
1. Check coolant and air in the system 

• Check coolant level: Make sure the coolant level is within the recommended range in the reservoir. Low coolant is a frequent cause of a heater not working. 
• Look for air pockets: If the heater only works when you accelerate, it often points to air trapped in the cooling system. You can try bleeding the system to remove air pockets, but consult your owner's manual or a mechanic for the correct procedure. 

2. Inspect the blend door and climate controls 

• Listen for noises: If you hear a clicking or grinding sound from behind the dashboard, it could be a failing blend door actuator. 
• Run a diagnostic: Some models have a diagnostic mode for the climate control system. To try this, turn the key to the "on" position (without starting the engine) and hold down the "recirculate" and "auto" buttons simultaneously. 
• Check for a blown fuse: A blown fuse for the climate control or radio system can cause the heater to stop working. 

3. Assess mechanical and component failures 

• Examine hoses: Inspect the heater hoses for any obvious blockages or leaks. 
• Check the thermostat: A faulty thermostat can prevent the engine from reaching the proper temperature needed for the heater to work correctly. 
• Consider the cabin air filter: A clogged or improperly installed cabin air filter can impede airflow, affecting both heating and AC performance. 

You can watch this video to learn how to troubleshoot climate control issues, including blend doors: 59sCar From Now OnYouTube · Jul 23, 2022
When to seek professional help
If these troubleshooting steps don't resolve the problem, it's best to consult a professional. A technician can accurately diagnose more complex issues like a faulty blower motor, a clogged heater core, or a failing blend door actuator, which may require extensive dashboard disassembly for repair.

What is the first symptom of a failed heater core?

Heater core failure symptoms
It will be pretty obvious if you are not receiving warm air inside the cabin or the defogging function isn't working well. This is the first sign that something may have failed – and clogging isn't the only culprit either.

What year Lexus IS250 to stay away from?

A: While the Lexus IS 250 is generally a reliable vehicle, the 2007 and 2008 model years are the ones you should avoid if possible. These two years have more reported issues compared to other model years, though they still perform better than the worst years of many other vehicle models.

Where is the heater core located?

The heater core is located inside the vehicle's passenger cabin, typically behind the dashboard on the passenger side. It's a part of the HVAC system that functions like a small radiator, using hot engine coolant to warm the air blown into the cabin.
 
This video shows the process of replacing a heater core in a 1990 GMC 1500: 1mSuburban RanchYouTube · Jan 9, 2021

• General location: Behind the dashboard, most often under the passenger-side section. 
• How to spot it: You can usually see the two hoses that connect the heater core to the engine's cooling system running through the firewall, often on the passenger side. 
• Accessibility: It is typically enclosed in a housing or case, which makes it difficult to access. Replacing it often requires removing a significant amount of the dashboard and interior components. 

This video demonstrates how to replace a heater core in a 1999-2007 GM Truck: 59sAnthonyJ350YouTube · Oct 9, 2022