Tips : Window Type Airconditioners

I was able to schedule today cleaning of our two window type air-conditioners. I engaged a home service and it took about 3 hours to clean two units. As expected the aircons were very dirty considering more than a year of not being cleaned. Both aircons had rust forming already. We have 5 year old 0.75HP Carrier Aircon no drip that was very dirty and with rust forming. We have a 3 year old 1.0HP York Aircon that was dirty and with a worst rust condition. The York Aircon has also its fan swing broken whereas that of the Carrier aircon was still working. Apparently, the Carrier aircon has better build quality given our experience.

Here are few tips from the aircon service person.
1. Aircon with no drip is not recommended as water left at the aircon can result to rust.
2. Aircon cleaning should be performed every three months to ensure longer life for the unit ie better air circulation and cooling,  lesser power consumption.
3. No additonal filters are needed to be installed with the existing aircon filter. Particles from the additional filters can accumulate at the fan and can cause damage.
4. Inverter type aircon consumes less power but parts are expensive and their availability is a problem.
5. Condura Aircon are recommended for their build quality ie sturdy plastic frame.

The service costed me 450pesos per unit. What's your personal experience with your airconditioners and how much does it cost you?