A/C not cooling fast enough

By Richard Hawkins, MACS Contributor

In the previous two weeks articles, we addressed the subject of “A/C Systems Not Blowing Cold Enough” and It still isn’t blowing cold enough. While on this subject, it seems like an ideal time to address a similar subject and one that MACS receives a lot of “hits” on in the search feature on the website. That subject is “A/C Not Cooling Fast Enough”. Please see figure 1.

Figure #1: The MACS website search feature with two articles that address cool down.

As was the case with systems  “not blowing cold enough”, there can certainly be a problem with the A/C system which is causing an issue with cool down time.  However, often it is a case of a customer expecting too much of their A/C system.   Here, we will focus on the latter.

When a vehicle sits outside in direct sunlight, a tremendous amount of heat can build up inside.  Even with relatively  mild summer ambient temperatures  (75° F to 80°F) vehicle interiors can easily reach temperatures of 125° F or more. Consider that this heat is not just in the air inside, but also in the seats, dashboard, floor board, roof, door panels, etc, (essentially the entire inside of the vehicle).

When it gets into the 90s and beyond, interior parts can get so hot that they can literally burn you when touched. Temperatures in the evaporator and ducts are also elevated and this is heat that has to be removed first, when the A/C is turned on. The larger the vehicle size, the more heat that has to be removed and the longer it takes for cool down to occur.  Please see figure #2.

Figure #2:  Temperatures can easily reach over 125° F in a parked vehicle in direct sunlight.

When the A/C is first turned on, the hot air flowing from the vents can actually make it initially feel like the temperature inside the vehicle is rising instead of going down. After this heat is removed and the vent temperature decreases, the remainder of the vehicle is acting like a gigantic heat sink radiating heat that the A/C system still has to remove.  As a result, the A/C system has to work very hard and sometimes the customers just expect too much of their system. They might also expect too much of a shop in trying to make an A/C system perform to a level that it just is not realistic.

Next week we will cover some more information on this subject and offer some suggestions to improve cool down time.

For now, we will leave you with a very important reminder.  NEVER LEAVE CHILDREN OR PETS IN A PARKED CAR IN SUMMER HEAT!!!!!  IT CAN PUT THEM IN EXTREME DANGER IN A VERY SHORT PERIOD OF TIME! We’re in the heat avoid tragedy and check your back seat.

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