PTC checking?

Get a good thermometer that reads air temperature (not an IR thermometer) and a stopwatch or timer app.

Position the thermometer in the airflow and start the car and the stopwatch.

When the thermometer needle begins to move, note the time.

Then let the car cool down again / next day:

pull the fuse for the PTC heaters

repeat the test.

If the time-to-change is the same on both runs, your PTC heaters may need work. If it's faster with the fuses in, well... they're working great.

In a normally working car you should see that needle twitch very quickly in response to the PTCs. It just doesn't move very far up because they are relatively small and weak- even at their best they only represent maybe 15% of the heating capability in the car.

As with any car if you want instant heat, get an electric seat warmer. They can be added over top, or installed in your existing seat.

 

The PTC heaters make a very small contribution, one you can barely detect when they're working right. They max out at about 700 watts, or about half a hair dryer, compared to the roughly 5,300 watts worth of heat you get from the coolant when it has warmed up. They don't make the air out the vents feel noticeably warm.

About the only way I can notice mine working is on a chilly morning with the windshield fogged; they do make a noticeable difference in when the glass begins to clear.

If you use Techstream you can turn them on and off. If you have a DC current clamp over one of the supplying wires, you should see current flowing.