The year 1990 marked the beginning of the Persian Gulf War and a challenging recession for the U.S. It was also the year that Ford Motor Company produced its first four-door SUV for the 1991 model year, the Ford Explorer.

The Explorer helped to trigger a craze for sport utility vehicles and this midsize SUV became quite popular from the late ’90s and early 2000s. But model years produced during this time period have some of the most irksome problems overall. Here are the top three that owners complain about thanks to data from RepairPal.com.

The Ford Explorer’s worn timing chain cassette

The third-most complained-about problem for the Ford Explorer was clicking or rattling noises caused by a bad timing chain cassette. 309 people reported this problem. A general diagnosis for this issue costs between $88 and $111. 

The solution to the problem, according to the automotive repair information website, was to replace the cassette and the timing chain tensioner. This repair would cost owners between $524 and $651, with labor costs running between $480 and $607 and parts at $44.

This problem was reported on model years 1996 through 2008 and 2010. Engines affected by it were the 4.0-liter V6, the 4.0-liter V6 SOHC, the 4.6-liter V8, and the 5.0-liter V8. The average mileage for the failing timing chain cassette was almost 142,000 miles.

Owners reported hearing a metallic rattle that sounded, according to one account, like “a wrench jumping around in the motor.” In a few cases, the timing chain cassette broke multiple times, resulting in bent engine valves. Fixing this problem was fairly labor-intensive, which meant that a mechanic would have to remove the engine or at least the flexplate.

The climate control that was out of control

Next up for the Ford Explorer‘s most irritating problems is a broken heater blend door that causes the heater to be stuck on the hottest setting. At the core of this problem is a failed actuator, which automatically moved the blend door to push hot or cool air through vents into the cabin. A clicking sound under the dash usually indicated that the actuator would need to be replaced.

417 owners reported the problem. Diagnosing the Explorer’s temperature control system costs between $88 and $111. Replacing the blend door actuator costs owners on average between $233 and $280, with labor costs between $175 and $222 and parts at $58. 

Model years affected by the bad blend door actuator were 1991, 1994 through 2010, and 2012 through 2014. The problem occurred on average at slightly over 111,000 miles. It actually occurred in a few cases as early as 30,000 miles. 

For some owners, the blend door actuator died at the most inopportune times. They would either have no heat in the dead of winter or the air conditioning would blow hot air in the summertime. One owner reported that his Ford Explorer’s blend door actuator failed twice.

A few owners bought a blend door replacement kit and fixed the problem themselves. Others received estimates from their mechanic or Ford dealership to replace the actuator, which ranged from $500 to $1,600.

The Ford Explorer featured a surprising crack on the liftgate

The most troublesome problem on the Ford Explorer was a cosmetic crack on its liftgate trim panel near the Ford emblem. The crack appeared following colder weather, seemingly overnight. 680 owners submitted complaints about this problem. RepairPal.com did not offer a repair estimate because Ford released instructions to owners for fixing it themselves.

The crack appeared on models produced from 1991 to 1994, 2000, and from 2002 to 2007. On average, this problem cropped up at about 91,000, although owners reported having it as early as 8,600 miles or up to 227,000 miles.

One owner reported having the defect repaired three times. Others said that their liftgates had multiple cracks. 

A Ford dealership fixed the problem free of charge for one lucky owner. Other Ford dealerships put the blame back on owners. Other owners fixed it themselves by either creating their own repair solution or by following the instructions Ford released. Ford did not issue a recall, however.

Some owners went to their mechanics, who estimated the repairs at anywhere from $450 to $1,500. 

Although these problems weren’t catastrophic in most cases, they still created trouble for owners of Ford Explorers across a wide range of model years. What’s more, owners reported instances of these problems happening repeatedly. It’s too bad that these model years of the Ford Explorer, which had a significant role in popularizing the SUV, couldn’t be a little more trouble-free.