The engine coolant temp sensor (ECT) has part in this. If the computer registers cool engine it dumps more fuel until warmed up. Just an idea.
Pressure can vary greatly from one system to another. It's best to record pressure immediately after cleaning the filters. This will be your base pressure. When the pressure rises 10-15 psi above the base rate, it is time to clean the filters.
The filters in an air purifier ususally need to be changed around every 3 - 6 months but it also depends greatly on what kind of air purifier you have .
Hot tub filters contain sand and gravel to filter our impurities in the water via a high pressure nozzle. The pressure must be high enough otherwise circulation problems may occur.
It is important to change the filters on your pitchers regularly. On average your filters should be changed about every 40 gallons or roughly 2 months.
I would look into the Hepa Filters, I ask your allegist if they have a recommediation. I have had real good luck with the hepa filters as long as you keep filters clean and changed.
All of them
Brita water filters are debated on safety. The filters do remove heavy metals, 99% of chlorine, and fluoride. The filters pose a danger because bacteria is not killed and if the filters are not changed properly the bacteria is in contact with the water.
Clogged fuel filters result in poor throttle response and lack of power. Filters should be ideally changed before that happens. The 2002 Trailblazer owner manual says fuel filter should be changed at 100k miles. I expect the 2003 manual makes some comment. I have a 2002 and just changed filters.
Some air purifiers do require a filter to be changed others have a filter that can be cleaned.
life.
2004 Sequoias do not have in cabin air filters.
Furnace humidifier filters should be changed at least every three months so they work efficiently. If not changed they trap dust and particles that can 'pollute' the air you breathe. http://yourfilters.com/