How Valley Metro keeps buses cool | Valley Metro
Valley Metro technicians maintain bus air conditioning systems

Air conditioning isn't an option in the Phoenix metro area. It's a necessity. Just imagine what life would be like here if it wasn't for air conditioning! Phoenix definitely wouldn't be the growing, thriving metropolitan area that it is now. They don't call it the Valley of the Sun for nothing! Triple digit temperatures are a guarantee in the summer months, and when it gets above 100 degrees, air conditioning is less of a luxury and more of a thing you simply can't do without.

That's especially true of transit. Bus riders like myself are no stranger to waiting in the heat for the next bus to come along. What a relief it is to finally board the bus and be blasted with nice, cool, refreshing air conditioning. But have you ever wondered how much work it takes to keep those AC units functioning properly?

Proper AC maintenance starts very early in the morning. In the summertime, buses are started at around 1 a.m. to allow the air conditioning to start working and get the interiors down to a target temperature of 72 degrees. Then they'll roll out at around 3 a.m. to start their routes. For the afternoon trips, it's even more important to give buses some extra time to cool down before they head out. Bus canopies help a lot in this regard, blocking as much of the Arizona sunshine as possible.

Valley Metro bus operations manager Joey Templeton says the air conditioner on a bus works differently than one on a typical vehicle.  Templeton says a typical car or truck takes the air coming through the vents at the front of the vehicle and runs it through a condenser, which is also at the front of the vehicle, to create cool air. On a Valley Metro bus, there are two condensers, one for the front of the bus, and one for the back. That way, cool air is distributed evenly throughout the entire vehicle.

A Valley Metro bus rider keeps cool in a bus on a hot day

There's another feature of Valley Metro buses that keeps things cool. The glass on our buses has a special film that not only tints the windows, but also blocks 99% of all UV light. That's a big help, since the more of that light is blocked, the cooler the inside of the bus will be. Templeton said tests showed that a bus with the treated glass was about 12 degrees cooler than a bus with traditional glass. Another adjustment was made to increase the speed of the blower motors on the bus to get cool air circulating as quickly as possible.

Templeton remarked that running a bus without air conditioning is an "absolute no-no." A bus that develops an AC problem during service will be taken out of service as soon as possible. Templeton also says running a bus with the windows open just isn't as good an idea as it might seem. It'll just blow hot air throughout the entire bus, making the air conditioner work that much harder to cool things down.

Of course, maintenance plays a key role in making sure every bus rolls out for service with a functioning air conditioning unit. In a previous blog, I talked about the army of dedicated technicians that keep our fleet of buses in tip-top shape. Templeton says a few of them work almost exclusively on air conditioning units. He added that every bus in the fleet is brought in for AC tests starting in December to make sure they're running properly in preparation for the hot summer months.

An open rear panel on a bus showing engine parts

So, the next time you're out on a blistering hot day and step into a nice, cool bus, you'll know that it takes a dedicated team of maintenance technicians and a lot of know-how to make it happen! If you’re interested in becoming part of our team, check out our career page. We’ll also be hosting a job fair on July 20th for maintenance technicians, operators, and more!

Alex Tsotsos
Alex Tsotsos
Rail Operations Communications Specialist
Writer, editor, musician, gamer, and former news professional. Frequently seen at Phoenix Rising matches and jogging around Gainey Ranch. May throw things in the presence of typos.